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Sleep is a life necessity, just like breathing. Sleeping too short or too long is associated with injuries, chronic health risks and early death. Many people have sleep problems, but do not take action. Athletes with sleep problems have a double risk of injuries. Evening- types are worse off, and eating late at night is a sleep wrecker. The Golden Trio in self- treatment to improve sleep are dietary adjustments, exercise at the right time a day, and a strict sleep hygiene. Supplements, day time naps, and catching up on the weekend are not advised.
Introduction
Sleep problems can have a huge impact on daily life, for example on work, sports performance and relationships. Even one hour less sleep per night increases the risk of accidents in traffic and at work. Ongoing sleep problems increase the risk of chronic diseases such as cardiovascular disease, obesity, and diabetes type 2.
Evening types are worse off than morning types, as well as people who work night shifts and at irregular hours. Also, women who do not receive treatment for menopausal symptoms suffer more from sleep problems. Hormones play a major role in sleep processes.
Athletes with chronic sleep problems have a significantly higher risk of injuries and impaired recovery from an injury, as well as decreased athletic development such as muscle growth.
The Golden Trio to optimize sleep quality is wholesome nutrition that includes the right type of vitamins, minerals and protein; moderate and high intensity exercise such as CrossFit in the morning; and a strict sleep hygiene.
In this article we dive deeper into the topic of sleep, injuries and health risks, and provide practical tips to improve your sleep. The five chapters in this article:
· Chapter 1: Sleep and sleep problems: Background info
· Chapter 2: Health risks of sleeping too short or too long
· Chapter 3: Sleep and athletic performance
· Chapter 4: The impact of nutrition, supplements, and exercise on sleep
· Chapter 5: Interventions to improve your sleep
Chapter 1: Sleep and sleep problems: Background info
In this chapter we discuss the following topics:
1. What is sleep?
2. What are sleep problems?
3. How many people experience sleep problems (especially on Sunday night)?
4. Why do we need to sleep?
5. What happens during sleep?
6. How is sleep regulated?
7. What is the main disruptor of sleep?
8. How do sleep patterns change during life?
9. Why are evening types worse off?
1. What is sleep?
Sleep is “a condition of body and mind that typically recurs for several hours every night, in which the eyes are closed, the postural muscles relaxed, the activity of the brain altered, and consciousness of the surroundings practically suspended”, according to the dictionary.[1]
According to science, sleep is a very complex process and more than just closing the eyes. It is defined as: “An active state of unconsciousness produced by the body where the brain is in a relative state of rest and is reactive primarily to internal stimulus.” Sleep can be distinguished from other states of unconsciousness such as coma and anesthesia, because it is reversible and self-regulating.
Although we spend 30% of our lives sleeping and at least 60%of the Dutch population have sleep problems, little is known about sleep and about how sleep is linked to health and performance. One reason is the variability of subjective and objective indicators used in studies to assess sleep quality. [2]
2. What are sleep problems?
Sleep problems refers to sleep deficiency. This is more than just sleeping too short or too long. It also includes sleeping at the wrong time of the day; or poor quality of sleep.
Sleep quality
Quality of sleep is a term with objective and subjective indicators. Objective indocators such as sleep duration and depth of sleep can be measured through the use of polysomnography and actigraphy. Subjective indocators refer to the retrospective evaluation of sleep experience via a sleep diary and self- reported questionnaires such as the Pittsburgh Sleep Quality Index (PSQI). This Index includes subjective sleep quality, sleep latency, sleep duration, habitual sleep efficacy, sleep disturbances, use of medications for sleep and daytime dysfunction in the previous month.
Sleep deficiency and poor quality of sleep are linked to health problems such as cardiovascular disease, obesity, diabetes type 2, and depression, as discussed later.
Sleep deficiency has become more common as society runs 27/4. Many people experience an obligation to be available many hours of the day for work or other activities, or their jobs demand working irregular hours or night shifts. Sleep is being squeezed into the time left after all other activities are done. Also blue and artificial light from phones and screens and lights from buildings in the living environment can have a disturbing impact on the quality of sleep.[3]
3. How many people experience sleep problems?
In a population based study from 2023, around 25% of Dutch adults reported having 'quite' or '(very) much' trouble sleeping in the past 2 weeks, such as not being able to fall asleep or to sleep through, or waking up too early. On average, women reported experiencing more problems than men, regardless of age.
In a study from 2019 among 1,228 Dutch adults, around 63% reported not being satisfied with the sleep quality. Sleeping through was reported as the major problem. Almost 50% reported waking up at night. Nevertheless, hardly anyone took measures to tackle the problems. Around 80% took screens to bed; 66% drank caffeinated drinks before going to sleep; and 68% drank alcohol in the evening, although most of the subjects were aware of the negative impact of these factors on the quality of their sleep. [4]
Social jetlag
Many people experience sleep problems on Sunday night. This is due to a deviant sleep pattern during the weekend of going to bed later and getting up later. This disturbs the natural biological clock of the body and leads to a disruption of sleep rhythm. Often, stressful thoughts and feelings of frustration of not being able to sleep exacerbate the situation. The so- called social jet lag.
4. Why do we need sleep?
There are at least four theories about the purpose of sleep:
According to the Inactivity theory, the main is to stay alive. From an evolutionary perspective creatures who are inactive at night were less likely to die from a predator’s attack in the dark, so being inactive at night was more beneficial to stay alive.
According to the Energy conservation theory, the main purpose of sleep is to reduce the use of energy, and (from ancient history) to not expend energy at times of the day or evening when hunting made little to no sense.
According to the Restorative theory, the main purpose of sleep is to repair and replete cellular components necessary for biological functions that become depleted throughout an awake day, such as muscle repair, tissue growth, protein synthesis, and release of many of the important hormones for growth.
According to the Brain plasticity theory, the main purpose of sleep is recovery and restoration of functions of the brain.
There are numerous explanations for why we sleep, and most likely a combination of explanations and theories offers the most complete picture on the purpose of sleep. Considering the fact that sleep deficiency is linked to several chronic diseases such as obesity, cardiovascular disease and diabetes type 2 and to mental health issues, sleep clearly seems to have a vital function. Many researchers claim vital processes happen during sleep, such as the repair and build of bodily tissue, the protection of the body against pathogens, and the processing of information and memories. [5]
5. What happens during sleep?
During sleep, we go through several sleep cycles that last an average of 90 minutes each. People go through 4 to 5 cycles per night.
Each cycle follows the same pattern. Each cycle starts with the Non- Rapid Eye Movement (NREM) phase that can be divided into subphase 1, 2 and 3, and a cycle ends with the Rapid Eye Movement (REM) phase. Each phase and subphase represent the depth of sleep and characteristics in brain wave, muscle tones, and eye movement. NREM takes 75 to 80% of total sleep, and REM the remaining 20 to 25%.
Although the duration of cycles is on average 90 minutes, the first cycle takes 70 to 100 minutes to fully complete, and the remaining cycles during the night take around 90 to 120 minutes. And as sleep progresses during the night, the REM phase takes longer per cycle.
NREM subphase 1 is the shallow sleep that takes up to 7 minutes and during which you can wake up easily. The following subphase 2 takes 10 to 25 minutes, and can take longer as sleep progresses during the night. Although this is a deeper sleep, you can still be woken up with a some effort (loud noise). It seems memory consolidation happens primarily during this subphase 2. Subphase 3 takes 20 to 40 minutes. This subphase is known as deep sleep or slow-wave sleep, referring to certain measurements of brain activity. Subphase 3 can take longer in earlier cycles of the night.
REM phase is the dreaming phase (although we also dream during other phases but less intense and lively) with total body voluntary muscle paralysis. This paralysis seems to be a mechanism to prevent neural stimuli from dreams to manifest in real actions during sleep. During REM the sympathetic system in the body is activated and although the limbs are paralyzed, brain activity, breathing, heart rate, blood pressure and eye movement are similar to when we are awake. It seems REM phase is important to guarantee adequate restorative sleep duration and sleep continuity.
REM phase is often affected by artificial lightning and this disturbs the completion of the sleep process, which is crucial for recovery. An adequate amount of REM sleep seems necessary to guarantee sleep continuity, and activating the brain and preparing it for the return to waking up. [6]
6. How is sleep regulated?
The mechanism through which sleep is regulated is an interaction and synchronization between two systems located within the brain and other body parts: Homeostatic mechanisms that form the body’s need for sleep regulated by the hypothalamus and brain stem; and circadian rhythms in the brain and other parts of the body. Circadian rhythms are the internal clocks of biochemical, physiological, and behavioral processes in the body, that fluctuate during on average 24.2 hours (our natural internal clocks take a bit longer than the 24 hours- society clock, and this difference may lead to sleep deficiency, as discussed later).
Little is known about why we sleep, about how homeostatic mechanism and circadian rhythms interact, and about why we need different phases of sleep. What is known, is that the interaction between the homeostatic mechanisms and the circadian rhythms results in an average of 8 hours of sleep per night, and that is it crucial for both systems to be synchronized.
Sleep pressure and adenosine
Pressure to sleep is a key aspect of homeostatic mechanisms. The pressure to sleep builds up in the body as time awake increases. The longer we are awake, the more the pressure is build up and we feel sleepy. Sleep pressure can decrease again by sleeping, and after a full night of good quality sleep, sleep pressure is low again.
Certain circumstances can increase the pressure to sleep and the feeling of sleepiness. For example infection when immune system is working overtime; cognitive demanding activities such as study; or physical activities such as sports as discussed later. The result of this increased sleep pressure is a longer and deeper sleep.
The neurotransmitter adenosine plays an important role in pressure for sleep. As time awake increases, adenosine level in the brain rises and the need for sleep increases. The function of adenosine can be disturbed by several factors among which stress (high cortisol levels), caffeine and certain drugs or medication.
Daylight, melatonin and cortisol
The circadian rhythms, the internal clocks for the sleep-wake cycle, are located in the brain and in other organs in the body, such as in muscles (Timing is everything in exercise).
Daylight is the main cue (the so- called zeitgeber) of circadian rhythms, with melatonin, produced in the pineal gland, as the main modulator. Daylight is received by the brain through the eyes. The suprachasmatic nucleus in the brain sends signals through the body via the sympathetic and parasympathetic system to align the body with the 24h rhythm of day and night. The brain signals the pineal gland to produce melatonin, based on the light level.
Melatonin levels increase in the evening when it gets dark, and peak in the early morning. When it gets light again, melatonin levels decrease and at the same time cortisol levels (the stress hormone) increase to help wake up in the morning.
The degree to which light impacts circadian rhythms varies: Circadian rhythms are the most sensitive to light in the morning and evening. Bright light in the morning causes a so- called phase advance: you get sleepy earlier in the evening and wake up earlier in the morning. Bright light in the evening causes a so- called phase delay: you get sleepy later in the evening and waking up later in the morning.
Furthermore, body temperature plays a role in circadian rhythms. Body temperature is higher in the morning and lower in the evening. This makes us feel more energetic in the morning and more sleepy in the evening. Exercise late in the evening affects this proces, as discussed later.
Disrupting zeitgebers
Light is the main zeitgeber for circadian rhythms. Other external zeitgebers can also affect circadian rhythms:
· Artificial and blue light can block there lease of melatonin.
· Lack of physical activity and lack of spending time outdoors can have negative effects
· Timing of food intake and food composition can disrupt circadian rhythm.
Circadian misalignment, which is defined as wakefulness and food intake occurring when the circacian system is promoting to sleep, can increase the risk of chronic diseases such as obesity, diabetes type 2 and high cholesterol levels, as explained later. (Timing is everything in nutrition).[8]
7. What is the main disruptor of sleep?
The main disruptor for the quality of sleep is desynchronization of the two mechanisms that regulate sleep.
Ideally homeostatic mechanism and circadian rhythms are perfectly synchronized, as shown in the left picture below. Sleep pressure builds up during the day as time awake increases, and sleep pressure is lowered during the night when we sleep.
The right picture below is a situation of a person working night shifts. It shows sleep pressure is build up and not fully lowered before going to work. Meanwhile wakefulness is at a lower level. This means the person is dealing with a huge need for sleep and is not fully awake and concentrated during the job. This can be a risk in certain jobs, often the jobs that are known for irregular hours and night shifts such as medical staff in hospitals.
8. How do sleep patterns change during life?
Aging
As we age, the interaction between the circadian rhythms and homeostatic processes changes. As a result, older people spend less time is subphase 3, the deep slow wave sleep. Some may not even experience this subphase anymore. Furthermore, people of 65 and above spend less time in REM phase and have an earlier wake time compared to younger adults.
Women and menopause
In women, sleep changes across the menstrual cycle. Short sleep duration is associated with irregular menstrual cycles. Pre-menstrual symptoms or menstrual cramps can affect the quality of sleep.
During the luteal phase after ovulation when progesterone is present, so called sleep spindle activity increases and REM phase is reduced. Sleep spindles are brain waves people experience during certain phases of sleep. These brain waves can be measured with an EEG. There is still little known about sleep spindles, but they seem to play a role in brain plasticity (learning and integrating new memories and knowledge), and in blocking our response to outside stimuli, such as loud noise, when we sleep. Furthermore, sleep spindles are indicators of NREM sleep and especially of subphase 2, the phase of deep sleep.
During the menopausal transition, hormone levels change, and fluctuations in hormone levels can cause menopausal symptoms such as sleep problems. (Hormones and vague symptoms). Research shows there is a strong association between menopausal symptoms and sleep problems. Estrogen seems to play an important role, although research is not fully conclusive on the exact mechanism behind female hormones and sleep problems. Other factors related to the ageing process can also contribute to sleep problems during menopausal transition, such as obesity, cardiovascular disease, gastrointestinal problems, urinary problems, hormonal problems, chronic pain syndromes, the use of medication, smoking, caffeine and alcohol. [10]
9. Why are evening types worse off?
Some people are morning types and others prefer the evening. This so- called intrinsic sleep–wake time preferences is classified in three chronotypes: the morning type, the intermediate type, and the evening type. Morning types prefer an early bedtime and early morning rise time. Evening types prefer a later bedtime and a late morning rise time, and intermediate types or somewhere in between. Morning and evening types have genetic differences and also differ the length of their circadian clocks, melatonin rhythms and sleep–wake times.
Switching your type can be achieved by following a strict regime, but eventually the body will always prefer to go back to your natural preference.
Health risks of evening types
Evening types have higher health risks compared to morning types. Research shows that evening types are more likely to develop unhealthy eating behaviors and become overweight. They have an increased risk for diabetes type 2, high cholesterol levels and high cortisol levels. They consume most of their calories closer to the time of melatonin secretion, which is the onset time of sleep. The increased health risks of evening types is not only linked to incorrect timing of food but also to other factors such as the preference for calorie- dense and high carb foods, as well as irregular eating patterns and skipping meals. (Timing is everything in nutrition).[11]
Chapter 2: Health risks of sleeping too short or too long
In this chapter we discuss the following topics:
1. How does sleep affect health?
2. Cravings, diabetes and obesity
3. Irritated bowel syndrome
4. Cardiovascular risks and daytime napping
5. Weakened immune system
6. Cancer
7. Mental health and brain disorders
8. Hormone disruptions
9. Early ageing
1. How does sleep affect health?
Sleep, nutrition and exercise are The Golden Trio for good health. Research on the associations between sleep duration and health outcomes in adults shows that the sleep duration that is most favorably associated with health is 7 to 8 hours per day. Sleeping too short (shorter than 6 hours per night) as well as sleeping too long (over 9 hours) are linked to several health risks, although sleeping too short seems worse.
Sleep deficiency (including sleeping too short and/ or too long) can lead to several molecular, immune, and neural changes in the body that play a role in the development and exacerbation of cardiovascular and metabolic diseases, as described below. Furthermore, sleep deficiency can lead to decreased cognitive and motor performance, comparable to the effects of excessive alcohol consumption. This increases the risk of traffic and work- related accidents, and sports injuries. Chronic sleep deficiency can even increase the risk of premature death.[12]
2. Cravings, diabetes and obesity
Research shows sleep deficiency is linked to the development of obesity, insulin resistance and diabetes type 2, and tot he exacerbate of existing endocrine (hormonal) conditions.
Hormonal changes
Sleep deficiency is associated with hormonal changes in the body. Lack of sleep and poor sleep quality lead to lower levels of the hormone leptin (the satiety hormone) and higher levels of the hormone ghrelin (the appetite stimulation hormone). This can lead to increased feelings of hunger and appetite, and cravings for calorie- dense foods and foods that a high in salt and sugar. Furthermore, fat metabolism changes when you eat at unusual times, such as during the night.
Behavioral changes
Poor sleep hygiene interacts with poor dietary choices such as increase portion size, increased calorie intake, increased feelings of hunger and increase intake of unhealthy food, as well as with reduced physical activity.
People who have insufficient sleep and a misalignment of circadian rhythms (for example due to working night shifts) burn on average 100 kcal more per day, but also have an increased energy intake of 250 kcal extra per day. It seems that this increased intake is not only related to hormonal changes that lead to increased hunger feelings, but moreover to impaired cognitive control of their diet.
Short sleep (less than 5 to 6 hours) as well as long sleep (over 8 hours per night) are linked to an increased risk of developing diabetes type 2 and obesity. Sleeping 4 hours for six nights in a row can already cause signs of pre- diabetes. Short sleep is one of the strongest risk factors for obesity. Adults with short sleep duration are 55% more likely to develop obesity (in children this is 89%). People who sleep less have a shorter REM phase and reduced REM activity, which seems to play a role in the link between weight gain and sleep deficiency. [13]
3. Irritated bowel syndrome
Sleep deficiency is linked to long-term inflammation of the digestive tract in inflammatory bowel disease. Sleep- deprived people with Crohn’s disease are twice as likely to relapse as people with good sleep quality.[14]
4. Cardiovascular risks and daytime napping
Sleep deficiency can lead to high blood pressure and hypertension, and increased cardiovascular risks. Also, working irregular hours and working in night shifts are related to this risk.
Short sleep duration (less than 6 hours) is linked to increased risk of a stroke and dying from coronary heart disease. Long sleep duration (longer than 9 hours per night) is also linked to hypertension, stroke and heart disease. Napping during the day only increases the risk for major cardiovascular events in people who sleep less than 6 hours, but not in people who sleep more than 9 hours. Research shows that on average 8 hours of sleep per night is associated to the lowest risk and incidence of cardiovascular disease.[15]
5. Weakened immune system
Research shows sleep is vital for immune system. Sleep deficiency can lead to a higher risk of infection for example with influenza. People who sleep less than 7 hours are almost 3 times more likely to develop a cold, than those who sleep 8 hours or more.[16]
6. Cancer
Short sleep duration and working in night shifts are both associated with an increased risk of breast cancer, colorectal cancer and prostate cancer. Women who sleep longer than 9 hours per night seem to have a decreased risk of breast cancer. [17]
7. Mental health and brain disorders
Sleep is important for several aspect of brain function such as cognition, concentration, and performance. During sleep the brain processes all information it received during the day. The brain forms new pathways to support learning new skills, to remember information, for decision-making, and for focus and creativity. Sleep is crucial for the relieve of stress and for the ability to deal with stressful situations.
Sleep deficiency seems to change activity in some parts of the brain involved in decision making, problem solving, emotional and behavioral control and stress management. Sleep deficiency is linked to impaired cognition, concentration and performance; to mental health problems such as risk- taking behavior, to depression and suicide; and to increased risks of brain diseases such as stroke, and dementia. [18]
8. Hormone disruptions
Almost every hormone in the body is released in response to circadian rhythms. This makes sleep crucial for hormonal function and regulation.
As described, sleep is linked to melatonin (to regulate the sleep- wake cycle and for the function of immune system); leptin and ghrelin (to regulate feelings of hunger and satiation); insulin (to regulate blood glucose levels); cortisol (to regulare stress); and estrogen and progesterone (to regulate female reproductive cycle and menopause).
Cortisol, estrogen, progesterone and thyroid hormone
Cortisol peaks within 30 minutes after waking up, giving energy to start the day. This peak triggers other hormones. Sleep deficiency can negatively impact cortisol release and cause a disruption of the levels of estrogen and progesterone. A bad night of sleep can cause cortisol levels to be high directly when waking up. This leads to a slow down of thyroid hormone and causes a slowdown of metabolism. High cortisol levels negatively affect the metabolism of fat, glucose and protein and can lead to more visceral (belly) fat and increased risk of chronic diseases. Sleeping 7 to 9 hours per night seems ideal for cortisol levels.
Growth hormone (somatotropin)
Growth hormone is released during sleep. It plays a crucial role in cell growth and repair; protein production and synthesis; muscle development; metabolism and immune system. Sleeping too short reduces the levels of growth hormone: it lowers the amount and production of growth hormone. Lower levels of growth hormone increase the risk of impaired recovery from training and from injuries. Furthermore, low levels of growth hormone negatively affect the metabolism of fat, glucose and protein and can lead to more visceral (belly) fat and increased risk of chronic diseases.[19]
9. Early ageing
The impact of increased levels of cortisol and higher activity of the sympathetic nervous system in cases of sleep deficiency, is similar to the effects of ageing. This implies sleep deficiency can increase the severity of age- related chronic diseases and disorders. [20]
Chapter 3: Sleep and athletic performance
In this chapter we discuss the following topics:
1. How does sleep affect athletic performance?
2. Impaired performance
3. Impaired learning of new skills
4. Impaired recovery
5. Overtraining
6. Increased risk of injuries
7. Impaired pain response
1. How does sleep affect athletic performance?
Research shows adequate sleep, in quantity and quality, can significantly improve athletic performance and mental health in athletes. The International Olympic Committee considers sleep health in terms of sufficient amount of sleep (at least 7 hours), proper circadian alignment, good overall perceived quality of sleep and absence of sleep disorders. Research shows elite athletes sleep less and have a lower quality of sleep compared to non- athletes, while poor sleep is a also predictor for sports injuries.[21]
2. Impaired performance
Sleep restriction of only a few hours in a night can result in increased physiological demands on the body, such as a higher heart rate during exercise, increased ventilation and respiratory frequency, decreased maximal oxygen uptake, reduced glycogen concentration in the muscles, and a higher lactate buildup.
Strength and power output for example in resistance training, decreases with lack of sleep. This decreased resistance to exercise seems to be caused by changes in the body as well as in the perceived effort by the athlete. This is neuromuscular fatigue: brain and body are tired.
Simply put: Athletes with sleep deficiency feel out of breath and exhausted faster. They are less strong, fast, accurate and concentrated in their performance.
Submaximal-effort sports such as biking seem to be more affected by sleep deficiency, compared to short maximum- effort sports such as weightlifting. This may be explained by the perceived effort, which increases with the increased duration of the effort.
3. Impaired learning of new skills
Research shows that learning and improving a motor skill continues 24 hours following training. NREM phase 2 sleep is correlated to consolidation of motor skills such as kipping pullups in CrossFit. The sleep following learning and practicing a new skill is crucial and significantly improves performance, and sleep deficiency can negatively affect this.
4. Impaired recovery
Sleep deficiency negatively affects recovery from exercise. The intake of glucose becomes impaired, which reduces muscle function and stamina, and leads to energy imbalances. This negatively affects both aerobic and anaerobic performance.
Sleep deficiency is linked to several hormonal disbalances, as described earlier. Decreased leptin, increased ghrelin and increased insulin resistance can lead to the intake of unhealthy foods, impairments in glucose metabolism in the muscles, and impairments in protein synthesis. All not beneficial for performance and recovery.
Furthermore, sleep deficiency leads to lower levels of growth hormone, higher levels of cortisol and weakening of the immune system. This hinders muscle recovery and repair and can eventually lead to imbalance of the autonomic nervous system.
5. Overtraining
Chronic sleep deficiency is linked to increased sympathetic nervous system activity and decreased parasympathetic nervous system activity. This means the body becomes in a chronic state of stress and is less able to relax and recover, and this can increase the risk of overtraining.
6. Increased risk of injuries
Research shows that athletes who sleep less than 7 hours per night for 14 days, are almost twice more likely to get injured (risk of musculoskeletal pain and sports injury), compared to those who sleep more than 8 hours. Also, the total duration of sleep depth was relevant: The more weeks, months or years of sleep deficiency, the higher the risk. Remarkably, these athletes also did not meet the recommended intake of fruits, vegetables and fish. The risk of muscle injury increases when decreased sleep duration is combined with increased training load.
Th eincreased risk of injury is also related to impaired brain functions due to sleep deficiency, such as not being able to respond adequately and fast to certain situations during sports. clso, Sleep deficiency can exacerbate feelings of anxiety in athletes, which is also linked to increased risk of injuries.
7. Impaired pain response
Pain can be a cause and a consequence of sleep deficiency. Sleep deficiency seems to have a de- activating effect on several systems in the body related to pain response, such as dopamine signaling and inflammatory responses. This can lead to pain amplification. Furthermore chronic pain, known among athletes, is often accompanied by insomnia, related to low grade neuro- inflammation. In these cases, the responsiveness to medical treatment is low. [22]
Chapter 4: The impact of nutrition, supplements and exercise on sleep
In this chapter:
1. How does nutrition affect sleep?
2. How effective are supplements, drugs or alcohol to improve sleep?
3. How does exercise affect sleep?
1. How does nutrition affect sleep?
Nutrition plays a significant role in sleep quality for several reasons among which the effect of nutrition on hormones involved in sleep processes in the body. Although the exact mechanism behind this effect is very complex because nutrients interact and every person has a unique response to food (Why your friend loses weight but you do not), research shows that the relationship between nutrition and sleep is bilateral, direct and indirect. For example, treatment of sleep problems improves appetite regulation and lowers the risk of obesity, and a healthy body weight is linked to better sleep quality. A healthy well balanced diet contains all nutrients that help to optimize sleep quality.
Sleep- improving nutrients
Certain foods that contain melatonin, tryptophan, vitamin D and GABA are linked to better sleep quality. A balanced wholesome diet with wholegrain products, vegetables, lean animal- and plant based protein, and unsaturated fats provides the body all these vitamins, minerals and proteins required for sleep quality. Furthermore, a healthy diet is beneficial for the microbiome of the gut, which is also linked to better sleep quality. (Your poop tells it all)
The unhealthy diet- shit show
An unhealthy diet that lacks essential vitamins, minerals and protein is linked to lower sleep quality. The intake foods high in calories and fat, as well as eating excessive amounts, and night time snacking can lead to sleep problems. Unhealthy diets can also trigger the development of several chronic diseases such as diabetes type 2. Sleep deficiency is associated with hormonal changes in the body that can lead to unhealthy food choices; changes in energy regulation; excessive food intake, increase feelings of hunger and craving, and reduced physical activity, as discussed earlier. Skipping breakfast, eating at irregular times, eating late at night, and eating excessive amounts of food are associated with poor sleep quality.
The type and amount of carbs matter
· Starch and sugar versus wholegrains, vegetables and fibers
Carb- rich products that lead to a fast peak in blood sugar levels and that are low in fibers such as white rice, white bread, refined grains, starch and sugar, are linked to poor sleep quality and a higher risk of insomnia. A diet with these types of foods causes an increase of blood glucose levels and as a result an increase of insulin levels, which triggers the release of several other hormones among which cortisol. This process can lead to sleep disorders. Furthermore, these type of products trigger inflammatory immune response; a disruption of gut microbiome; and the onset of chronic disease. All linked to sleep deficiency.
Carb- rich products with less peak- impact on blood sugar levels and that are high in fibers, such as wholegrain products and vegetables, are linked to better sleep quality, a lower risk of insomnia, less inflammatory response, improved gut microbiome and protection against the development of chronic diseases.
· Low carb and high carb diets versus moderate carb
Total amount of carbs in a diet is relevant. Low carb diets with in which less than 40% of the total calorie intake is delivered by carbs, as well as high carb diets in which more than 70% of the total caloric intake is delivered by carbs, seem to increase the risk of sleep deficiency and can have a negative effect on deep slow wave sleep and on the onset of REM phase. A moderate intake of carbs, around 50 to 60% of total caloric intake, seems the most beneficial for sleep quality.
· Carbs in the evening versus during the day
Eating a high- carb meal in the evening reduces the secretion of melatonin and delays circadian rhythm and therefor negatively impacts sleep quality. Eating a meal with a moderate amount of carbs in the morning and during the day seems the most beneficial for sleep quality.
The type of fat matters
· Unsaturated versus saturated fats
The intake of fatty fish seems to have a positive effect on the quality of sleep. Fatty fish contains omega 3 and omega 6 fatty acids and vitamin D. These nutrients seem to influence the regulation of serotonin (the precursor of melatonin) and therefor of sleep. Eating fatty fish also seems to increase sleepiness. Fish, meat and eggs contain the unsaturated fatty acid arachidonic acid, that has a sleep promoting effect.
A diet that lacks omega 3 is associated with impaired sleep because of the disturbing effect on melatonin secretion. A diet high in saturated fats, for example in fried products, is linked to increased wakes at night and shorter slow- wave sleep phase. Research shows people with insomnia consume more foods that are high in saturated fats, the fats that contribute to the development of chronic diseases such as cardiovascular disease, diabetes type 2and obesity. All associated with sleep deficiency.
The type and amount of protein matters
· Low versus moderate protein intake
The body depends on nutrition for essential amino acids (protein). The intake of a sufficient amount of essential amino acids, specifically of tryptophan, is beneficial for sleep quality. Tryptophan is the precursor for serotonin. A low protein diet, in which less than 16% of total caloric intake comes from protein, is linked to difficulty falling asleep and poor sleep quality. Too little protein can lead to a tryptophan deficiency. The adequate amount of protein needed depends on many different factors including one's health status and physical activity level. Too high a protein intake might also trigger sleep deficiency.[23]
2. How effective are supplements, drugs or alcohol to improve sleep?
Research on the efficacy of dietary supplements such as melatonin, vitamin D, tryptophan and GABA to improve sleep is inconclusive and scientific evidence is not solid. This is due to several reasons including poor research design; the subjectivity of reporting sleep quality; and the incomparability of studies; or the selection of the population a study focused on.
It is advised to optimize the level of these nutrients by eating the right food products in the right amounts at the right time a day, as well as by making lifestyle adjustments, before considering dietary supplements. Nutritional and lifestyle adjustments are easy, safe and no regret solutions, that will also help to improve overall health. Hormone Therapy can improve sleep during menopause. The use of drugs and alcohol leads to poorer sleep quality.
Melatonin and vitamin D
The use of melatonin supplements has increased over the years. There is a widespread concern about vitamin D deficiency because people do not spend enough time outdoors, (the so- called light deficiency), and about melatonin deficiency from overexposure to artificial light (the so- called darkness deficiency).
Vitamin D deficiency is linked to a higher risk of insomnia, shorter sleep duration, poor sleep quality and daytime sleepiness. Furthermore, a vitamin D deficiency can cause non-specific pain which can affect sleep. The Dutch Health Counsil recommends a daily intake of 10 micrograms of vitamin D for the Dutch adult population.
Research on the efficacy and safety of melatonin supplements shows that melatonin can interact with medication, nutrients and herbs that are known for activities such as blood thinning, blood sugar lowering, blood pressure lowering, anti-depressant or immuno suppressing. Furthermore, the dose and timing of melatonin intake seem crucial, and incorrect timing can has adverse effects. Also, taking melatoninsupplements seems to suppress and disrupt the body’s own melatonin production. In many cases, a melatonin deficiency is not the cause of sleep deficiency, and taking extra supplements may disrupt sleep processes. In certain situations there may well be a melatonin deficiency, or lower melatonin levels, such as in people with autism and in the elderly over the age of 60. Therefore, it is advised to first consult a health professional before taking melatonin supplements.
Dietary adjustments and lifestyle changes can help to optimize the body’s own melatonin levels:
1. Use bright light in the morning when waking up, use dimmed light in the evening to stimulate melatonin production.
2. Reduce artificial and blue light in the evening
3. Ensure a sufficient intake of protein (tryptophan) and anti-oxidants with anti-inflammatory effects (in vegetables, fruit, nuts and seeds).
4. Ensure the intake of foods sources with blue light protective effects such as lant based compounds in spinach, pistachios, eggs and bell peppers.
5. Take a vitamin D supplement of 10 micrograms per day and spend at least 30 minutes per day outdoors.
Tryptophan
Melatonin is formed in the process of tryptophan conversion into serotonin. Tryptophan deficiency in the diet is linked to sleep deficiency and poor sleep quality. Tryptophan is in product such as oats, poultry, eggs, fish, beans and pumpkin. Tryptophan is a precursor of melatonin and serotonin, and an essential amino acid the body cannot synthesis but must receive through food. The conversion of tryptophan into serotonin only occurs if levels of tryptophan are sufficient enough.
GABA
GABA, found in some fermented dairy products, soy beans and many vegetables, is involved in the regulation of both the REM and the NREM sleep phases. GABA seems to have positive effects on metabolic disorders. It can increase sleep efficiency and can have hypnotic effects.
Hormone therapy during menopause
Research shows hormone supplementation with low dose of estrogen and progesterone is effective in treatment of menopausal symptoms such as hot flashes, night sweats and disrupted sleep duration.
Alcohol, caffein, nicotin and cannabis
Alcohol
Alcohol, although sometimes perceived otherwise, has a negative impact on sleep. Alcohol consumption up to 6 hours before bedtime impairs the quality of sleep. The intake of 1 glass of alcohol results in a shorter REM sleep phase and repeated alcohol consumption in the evening leads to a lower slow wave deep sleep. Alcohol users are often more sleepy during the day compared to non-alcohol users.
Caffeine
Drinking caffeine can disrupt the quality of sleep. The half- life of caffeine caries from 2 to 20 hours. It seems that people who consume large amounts of coffee during the day, are more tired in the morning.
Nicotin
Nicotin in cigarettes, patches or pills, increases the risk of sleep deficiency including sleep disturbances, increased sleep delay, more difficulty maintaining sleep, and more daytime sleepiness. Nicotin disrupts the balance of neurotransmitters that are involved in the regulation of sleep.
Cannabis
Cannabis can have positive effects on sleep quality if it is used for a short time. It can have negative effects such as more sleep disturbances if it is used for prolonged time. [24]
3. How does physical activity affect sleep?
The relationship between physical activity, exercise and sleep is bilateral, direct and indirect. Physical activity and exercise can help to build up sleep pressure and result in a longer and deeper sleep. Moderate and high intensity aerobic exercise and resistance training, such as CrossFit, seem beneficial for the treatment of sleep disorders. A proper sleep quality improves physical performance and lowers the risk of injuries. The intensity and timing matter.
More sleep pressure and deeper sleep
Physical activity (defined as activities that cause energy expenditure such as household or garden activities) and physical exercise (defined as structured and repetitive activities to maintain or improve health) can improve the quality of sleep.
Regular exercise increases the deep- sleep phase. This seems the result of increased energy expenditure during the day, especially after exercising in the morning. During exercise the core body temperature rises. The body responses by lowering the temperature, which is beneficial for a deep sleep.
Furthermore, exercise has a positive effect on blood pressure. A high blood pressure, above 115/75 mmHg. increases the risk of cardiovascular disease. This risk doubles with every increase of 20/10 mmHg. Sleep deficiency correlates with hypertension and an increased risk of cardiovascular disease. Under normal healthy circumstances, blood pressure decreases during the night with 10 to 20%. Physical activity and exercise during the day seem to lower blood pressure at night.
The intensity, timing and location matter
· Moderate and high versus low intensity
Especially for people over the age of 65, more and longer physical activity is associated with better sleep and less fatigue during the day. Older people who are active at moderate to high intensity level report a better sleep quality, longer sleep duration and less time needed to fall asleep, compared to older people who are not physically active. Very light physical activity does not seem to improve sleep quality.
· Morning versus evening, outdoors
Moderate and high intensity aerobic exercise and resistance training such as CrossFit, done regularly, in the morning or during the day,p referably outdoors, has positive effects on sleep quality. It can lead to weight loss which is beneficial for people with sleep disorders such as sleep apnea; it improves melatonin secretion; and it increases activity of the upper respiratory tract which is beneficial for good sleep. Physical activity outdoors such as brisk walking, also has beneficial effects on sleep. There are indications that specifically morning exercise might improve quality of sleep and circadian rhythms.
High intensity exercise late at night negatively affects the secretion and concentration of melatonin, even within a few minutes. Exercise late at night can also cause sleep disruption because of the physical arousal. Therefor, it is advised to exercise in the morning or at day time, and a the latest at least three hours before bed time. [25]
Chapter 5: Interventions to improve your sleep
In this chapter:
1. How is the quality of your sleep?
2. How helpful are sleep apps?
3. How effective is catching up sleep during the weekend?
4. How to optimize sleep quality and solve sleep problems?
1. How is the quality of your sleep?
Much is still unknown about sleep. However, it is clear that sleep is, in many ways, crucial for physical and mental health and for athletic performance. Sleep deficiency can have a major impact on daily life, and often is the result lifestyle choices, environmental conditions, or underlying medical conditions. How well we sleep is partially within our control, at least as far as lifestyle choices. If we can make choices that are unfavorable to our sleep, such as drinking caffeine or alcohol late in the evening, we also have the ability to make more favorable choices and actively take control over our health. Relatively simple changes in daily life can result in significant improvements in sleep.
Not me…
Research shows 45% of Dutch adults is dissatisfied about their sleep and would like to improve it, but do not take action to do so. About 73% of Dutch adults know screen time before bed negatively affects the ability to fall asleep, yet 94% watch screens within one hours before bed time. Around 60% know caffeine and alcohol negatively affect the quality of sleep, yet almost 70% drink caffeine-rich drinks or alcohol before going to bed. Over 90% know being active during the day enhances the quality of sleep, yet over 50% are not active enough. Last, around 78% of Dutch adults know going to bed and waking up at the same time every day, even on the weekend, helps to sleep better, yet over 70% do not do this.
Sometimes we have no idea why it is that we sleep so badly, when there are clearly identifiable causes. Sometimes our self-image does not match the facts. Sometimes, what is true for another is not true for ourselves. Getting insight into the facts is the first step to improve sleep.
Sleep diary
Quality of sleep is an objective and subjective concept, as mentioned earlier. It is known that on average 7 to 9 hours of sleep per night seems best for adults. A diagnostic tools such as a sleep diary or the Pittsburgh Sleep Quality Index to track sleep duration and quality of sleep, can be helpful to pinpoint the problem.
2. How helpful are sleep apps?
Sleep apps are easy to use and low- cost. The most frequently provided functions by apps are sleep monitoring, measuring sleep, providing alarms, and recording sleep using a sleep diary.
There are concerns regarding the use of sleep apps such as about accuracy, privacy, security and information quality. Research shows only few sleep apps contain empirical evidence supporting their claims. Often this evidence is based on methodological limitations. The overall effectiveness of sleep apps remains unknown. Some sleep apps produce many false positive outcomes.
Research on the efficacy of mHealth apps to improve health behavior and sleep, remains inconclusive. Some studies show successes in promoting sleep, while other studies report that sleep apps can lead to adverse and unhealthy obsessive behavior regarding sleep.
3. How effective is catching up sleep during the weekend?
A lack of sleep during the week cannot be compensated by sleeping longer during the weekend. For one, because a lack of sleep of 2 hours per night would mean you would have to sleep at least 10 hours extra on the weekend. Furthermore, the negative health effects of sleep deficiency, for example the disruption of hormones, cannot be made undone during the weekend. And, as already described earlier, daytime naps are not beneficial to improve sleep, or health. Resisting the need to sleep during the day,might be hard, but can help to build up sleep pressure for the next night.
4. How to optimize sleep quality and solve sleep problems?
The first step in optimizing sleep quality and solving sleep problems is to develop daily habits such as healthy nutrition, exercise during the day and exposure to daylight during the day, as well as to create optimal conditions to improve sleep. The latter is known as sleep hygiene. Additionally there are tips on what to do after one or more bad nights. In case of persistent sleep deficiency, the stimulus- control technique can be helpful.
Optimize sleep hygiene
Sleep hygiene refers to optimizing conditions and daily habits to improve sleep. This involves:
· Aim for 7 to 9 hours of sleep per night.
· Go to bed and wake up at the same time every day. Especially waking up at the same time seems important. (even on the weekends).
· Perform the sameroutine every evening at least one hour before going to bed: Shut down screens, finish all activities, prepare for bed, meditate to calm down more.
· Write down worrying thoughts with pen and paper, not a screen, and put it out of sight.
· Have a well-ventilated, cool, dark and quit bedroom. Use a sleep mask or earplugs.
· Remove all distractions from the bedroom: screens, work, hobbies.
· Avoid eating shortly before going to bed, or drinking caffeine and alcohol at least a few hours before bed time.
· Avoid intense exercise late in the evening, at least three hours before bed time. A calming outdoor walk can be helpful.
Tips after one or more bad nights of sleep
· Immediately pick up the sleep hygiene. Go to bed and wake up at the same time and perform your bed time routine.
· Avoid daytime naps. Sleep pressure needs to build up again, and the body and brain need to be reset and trained to go back the regular sleep rhythm.
· Limit excessive sugar or high- carb intake the day after one or more bad nights.
· Do not compensate during the weekend.
Stimulus- control technique in case of persistent sleep deficiency
The goal of the stimulus-control technique is to improve the association between the bed (bedroom) and sleep. The four guidelines of this technique are:
1. Only go to bed when you are sleepy, otherwise step out of bed
Sleep pressure must be high enough to sleep. Just lying in bed when you do not feel sleepy, even though it is bedtime, often leads to stress, frustration and thoughts such as: I need to sleep now because I need 8 hours of sleep because I have to get up early tomorrow. Compulsively staying in bed while not feeling sleepy weakens the association between sleep and your bed. The advice is to get out of bed, do something relaxing like meditate, and thus re-establish sleep pressure.
Not feeling sleepy is not the same as having another rebound in the evening after you initially did feel sleepy. In the latter case, the sleep pressure did turn out to be high enough and you will soon feel sleepy again when you are in bed.
2. Use the bed only for sleeping or intercourse, not for any other activities such as screen time
By using the bed only for sleep, the association between the two is strengthened. This increases the change of better quality of sleep.
3. Do not sleep anywhere else outside the bed, for example on the couch
This also helps to strengthen the association between bed and sleep. Not sleeping anywhere else helps to build up sleep pressure for better sleep.
4. Reduce your time in bed (the sleep restriction)
Sleep restriction is a technique applied in case of persistent sleep problems. The aim of this technique is to improve sleep quality and especially deep sleep and time falling asleep; and the association between bed and sleep, by limiting bed-times.
The steps in this technique are:
a. Keep a daily diary for two weeks in which you track how many hours you think you have slept that night (not: how many hours you laid in bed)
b. Calculate your average hours of sleep per night based on the diary (for example 6 hours)
c. Calculate your ‘sleep efficiency score’. This is number of hours slept divided by number of hours spent in bed x100. Ideally this score is above 85.
d. Add 1 hours to your average (6+1= 7). This is the total hours you are allowed to lay in bed for the next two weeks. No more/ less, regardless of if you actually sleep.
e. After two weeks, recalculate your ‘sleep efficiency score’.
The preconditions for this technique are:
- The minimum hours you are allowed to lay in bed for those next two weeks cannot be less than 5. The maximum hours you are allowed to lay in bed in 8.
- Daytime naps are not allowed.
- Be aware that the first few days problems may increase.
- This technique is not advised in case of underlying medical (physical or mental) conditions, mental health issues, or sleep disorders such as sleep apnea
- This technique is not advised in for people in certain occupations such as drivers or operators of hazardous machinery. [26]
Concluding
Sleep is a life necessity, just like breathing. Sleeping 7 to 9 hours per night seems optimal for most adults. Sleeping too short or too long is associated with injuries, chronic health risks and early death. Many people have sleep problems, but do not take action. Athletes with sleep problems have 2x higher risk of injuries. Evening types people are worse off.
Sleep deficiency is often the result lifestyle choices, and is therefor within our control. Getting insight into your habits is the first step to pinpoint the problem.
The Golden Trio in self- treatment of sleep problems are dietary adjustments, exercise at the right time a day, and a strict sleep hygiene. Supplements, daytime naps and catching up on the weekend are not advised. Adapting your rhythm of life to your natural biological clock is relevant.
A wholesome well balanced diet with whole grain products, vegetables, some fruit, lean animal-based and plant-based protein, unsaturated fats and only minimally processed foods provides the body all the nutrients for optimal quality of sleep and for overall health (How artificial is your food?), when eaten in moderate amounts during the day.
Regular moderate to high intensity aerobic and resistance training such as CrossFit, in the morning or during the day, preferably outdoors, helps to improve the quality of sleep and overall health. Meeting the World Health Organizations' recommended activity level is the minimum for maintenance of health. This means doing at least 150 to 300 minutes of moderate/ high intensity aerobic training with at least 2 times per week resistance training at moderate/ high intensity and balance training, as well as limiting time sitting down.
A strict sleep hygiene includes having an evening routine, minimizing artificial light and optimizing bed room circumstances to improve sleep quality. In case of persistent sleep deficiency, the sleep restriction technique is challenging but may offer a solution for some.
Create your own health!©
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