Diet and sleep: The expanded story and critical take-home messages.
I’ll break this up into sections and repeat the take-home messages for better remembrance.
A crucial relationship between diet and sleep exists and it is, with many things in life, reciprocal.
Our nutritional intake influences sleep quality and duration. Conversely, high quality sleep improves eating choices.
Diets rich in saturated fats, processed foods and sugar can sabotage restorative sleep by fragmenting sleep cycles and reducing the quality of sleep phases.
The symbiosis is powerful; poor sleep can skew our dietary choices, increase cravings for high-calorie, sugary foods, thus setting the stage for a loop of bad food cravings and compromised sleep. The time of day we consume certain foods similarly plays a role, with late-night meals and caffeine disrupting circadian rhythms causing us to ignore our sleep-drive peak.
It doesn’t matter which you begin to improve - diet or sleep - as either will have a positive impact on the other.
Dietary patterns and sleep quality.
A diet high in saturated fats is harmful to sleep quality. A study published in the Journal of Clinical Sleep Medicine found that higher saturated fat intake led to less restful sleep, characterised by fewer slow-wave sleep patterns; the deer and most restorative sleep phases. Diets high in saturated fat appear to disrupt circadian rhythms, the body's innate sleep-wake cycle, potentially leading to difficulties in sleep initiation and maintenance.
The importance of fibre in the diet has also been connected to sleep. In contrast to diets high in saturated fats, diets abundant in fibre have been correlated with more time spent in the slow-wave sleep stage, as per research published in the Journal of Clinical Sleep Medicine.
Dietary fibre aids in the maintenance of a balanced gut microbiome and regulates blood sugar levels, both of which can influence neurotransmitter pathways and hormonal signals that govern sleep.
Sugar consumption has been closely scrutinised. Excessive sugar intake, particularly close to bedtime, has been shown to result in more awakenings. A study in the Journal of Sleep Research indicates that higher sugar intake was linked to more restless, fragmented sleep. The surmised mechanism involves blood sugar fluctuations that can result in periods of wakefulness. Additionally, sugar can hinder the activity of orexin, a neurotransmitter that helps regulate arousal, wakefulness, and appetite; impaired orexin function is related to sleep disruption.
Not surprisingly, micronutrients, the vitamins and minerals found in various foods, play a role in regulating sleep. Magnesium, for instance, has been shown to support sleep by maintaining levels of GABA, a neurotransmitter that promotes relaxation and sleep. Deficiencies in magnesium, highlighted in studies like those in the Journal of Research in Medical Sciences, have been linked with disturbed sleep patterns and insomnia. Similarly, inadequate levels of vitamin D have been associated with sleep disturbances, as found in a review in the journal ‘Nutrients’. At least 10 to 30 minutes of moderate sun exposure 3 times per week or more is recommended to maintain vitamin D levels.
Iron is an essential micronutrient and is implicated in restless legs syndrome, a condition that can significantly interfere with sleep onset and continuity. Vitamin B12 and folic acid deficiencies have also been correlated with insomnia and abnormal sleep patterns.
Macronutrients, composed of carbohydrates, proteins, and fats, also impact sleep. Diets with a high glycemic index, typically high in processed carbohydrates, have been associated with difficulty in sleep onset. On the other hand, diets balanced with complex carbohydrates and lean proteins can help facilitate the onset of sleep due to their ability to aid in the production of serotonin, a precursor to melatonin, the hormone that signals sleep to the body.
Obesity and Sleep.
Overeating and obesity significantly contributes to the risk of developing sleep-related disorders such as Obstructive Sleep Apnea (OSA). The accumulation of excess body fat, particularly around the neck and abdominal area, can physically encroach on the airway. This mechanical compression, especially when lying down, causes greater chances for airway obstruction during sleep. When the airway is intermittently blocked, it results in reduced oxygen levels and fragmented sleep patterns due to repeated awakenings, characteristic of OSA.
Physiological effects of obesity imparts a chronic state of low-grade inflammation, which can exacerbate the swelling in the airway tissues, further restricting airflow during sleep. Obesity also influences hormonal imbalances that can impact sleep architecture. For instance, increased fat stores can lead to elevated levels of leptin, a hormone that regulates appetite and energy balance but is also linked to respiratory dysfunction at night.
Excess weight often correlates with increased resistance to insulin (such as diabetes or pre-diabetes) which causes metabolic disruptions that can indirectly affect sleep quality through altered glucose metabolism and increased nighttime awakenings.
One of the first steps to ensuring you’re on the right path to a restful night's sleep is to keep your BMI between 18 and 25. BMI is calculated via: Weight (kg) / height (m)². More useful perhaps, is to ensure your body fat percentage is between 10% and 18% if you’re male, and 15% to 30% if you’re female. Smart scales can provide information on your body mass composition.
Foods that disrupt sleep before bed.
Fatty foods, spicy foods, caffeinated drinks and alcoholic drinks can have a disruptive impact on sleep when consumed close to bedtime.
Fatty foods tend to be digested slowly and can cause discomfort or gastrointestinal reflux. Spicy foods can have similar effects and may cause heartburn. This discomfort can make it hard to fall asleep or stay asleep.
Caffeinated foods and beverages are well-known sleep disruptors due to their stimulant effects (by blocking adenosine receptors in the brain), which can increase alertness and prolong sleep onset times. They can also fragment sleep, leading to lighter and less restorative sleep phases.
Alcohol might initially induce drowsiness; however, it's metabolically disruptive, leading to non-restful sleep in the second half of the night. It significantly reduces REM sleep, the stage associated with dreaming and memory consolidation. Alcohol can also exacerbate breathing problems, posing a particular threat to those with sleep apnea.
As a general rule of thumb, the closer you consume caffeine or alcohol before going to bed, often the more of an impact it can have. It should be noted that while alcohol can sometimes help with sleep onset, the initial relaxing effects are quickly negated by the disruptive effects caused by breaking the substance down in your body. For most people, one glass of wine a few hours before winding down should not significantly impact sleep. This
Those who suffer from alcohol use disorder will sometimes build a dependency on alcohol to fall asleep. This dependency is not unsimilar to sleeping-pill dependency where both substances have a temporary sedative effect and can be highly addictive upon an individual circumstance. If you suspect you have a dependency issue, please raise this issue with your doctor.
Sugar and Sleep.
Recent research (such as a study in the Journal of Sleep Research) explores the link between high sugar intake and fragmented sleep. Excessive sugar consumption disrupts blood sugar balance, which can lead to frequent awakenings and prevent the body from entering restorative stages of sleep. Compromised sleep can quickly perpetuate a cycle of fatigue and impaired judgement, often resulting in an increased craving for sugary foods for quick energy the following day. This creates a vicious cycle of sleep deprivation and unhealthy eating habits that can significantly impact overall health and mental well-being.
To break the cycle, it is crucial to adopt a mindful approach to eating and a consistent sleep routine. Reducing sugar intake, especially later in the day, and incorporating more complex carbohydrates with low glycemic indices can stabilise blood sugar levels and improve sleep. Nutrient-dense foods like whole grains, lean proteins, and healthy fats support sustained energy levels and satiety throughout the day. Coupling this dietary shift with good sleep hygiene: preparing a restful environment, establishing a regular bedtime, and minimising exposure to screens before sleep, can significantly enhance sleep quality. By making these changes, you can effectively fix the cycle of sugary diets / cravings and poor sleep.
Examples of Sleep Promoting Complex Carbohydrates:
- Buckwheat
- Bulgur wheat
- Potatoes
- Carrots, Chickpeas, Peas & Broccoli
- Whole Wheat & Multi Grain Bread
- Rolled Oats
- Quinoa
- Barley
- Brown and Wild Rice
- Whole grains
- Whole Wheat Pasta
Diet plans that improve sleep quality.
The pursuit of better sleep through nutritional choices has led to interest in various dietary patterns, notably the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) have been observed to improve sleep quality.
The Mediterranean diet, abundant in fruits, vegetables, whole grains, olive oil, and lean proteins such as fish and poultry, emphasises food high in fibre and low in saturated fats. This diet is also rich in vitamins and minerals known to support healthy sleep patterns. A study in the journal "Frontiers in Nutrition" highlighted that adherence to the Mediterranean diet was associated with improvements in sleep quality in older adults.
Similarly, the DASH diet, which was originally developed to lower blood pressure, also shows promise for improving sleep. It shares similarities with the Mediterranean diet, focusing on fruit, vegetables, whole grains, and low-fat dairy, while also reducing sodium intake. Research, such as the study published in the "American Journal of Lifestyle Medicine" has observed that the DASH diet can contribute to better sleep, potentially by reducing the stress on the cardiovascular system and improving comorbid conditions linked with sleep disturbances.
Both diets favour reductions in red meat, sweets, and high-fat foods, promoting nutrients that are conducive to relaxation and sleep, like magnesium, potassium, and healthy fats. Embracing diets like these is a fast and easy way to improve your sleep.
Power Foods for Better Sleep.
Nature provides us with an array of 'power foods' that can facilitate a peaceful night's rest.
Kiwi-fruit is a good source of antioxidants and serotonin, which the body converts into the sleep-inducing hormone melatonin. Findings from a study in the Asia Pacific Journal of Clinical Nutrition suggest that consuming kiwi fruit before bedtime may improve sleep onset, duration, and quality.
Nuts: Almonds, walnuts and pistachios are not only heart-healthy snacks but also double as sources of melatonin and magnesium. Magnesium has a relaxing effect and aids in the production of sleep hormones and neuropeptides such as a GABA which is often considered as a key calming compound promoting sleep onset. Nuts also contain Zinc which contribute to sleep regulation and brain health.
Oily fish such as salmon, trout, and mackerel are rich in omega-3 fatty acids and vitamin D and have been linked in studies, like the one from the Journal of Clinical Sleep Medicine, to the regulation of serotonin. Their nutritional profile supports the production of sleep-regulating substances, potentially leading to longer, more restful sleep.
Milk and Dairy: Dairy contains the amino acid tryptophan, which the body uses to produce serotonin, a neurotransmitter that helps with relaxation and well-being. Serotonin is also a precursor to melatonin, the hormone that regulates sleep cycles. A warm glass of milk, some cheese or even some dark chocolate may help with relaxation before sleep.
Oats also contain melatonin and tryptophan, helping regulate sleep cycles and increase production of serotonin. As a complex carb, oats help in the production of insulin which helps deliver tryptophan to the brain. Oats are an excellent choice as they’re packed with essential vitamins and minerals such as B vitamins, magnesium, and iron. B vitamins are involved in the regulation of tryptophan and synthesis of serotonin and melatonin, where magnesium helps relax the nervous system and iron is thought to help ease symptoms of restless leg syndrome.
Cherries, particularly tart cherries, are another sleep-friendly choice. They are one of the few natural food sources of melatonin, and studies, like one reported in the European Journal of Nutrition, have identified their juice as beneficial in increasing both sleep quality and duration. Their anti-inflammatory properties also serve as an added bonus, potentially easing conditions that might disrupt sleep.
Incorporating these foods into your diet can be a rewarding strategy for enhancing sleep quality. They work in harmony with your body's natural processes to help with deeper and more restorative sleep cycles.
The Role of Hydration and Sleep.
Hydration holds a dualistic influence on sleep; it's as essential for our bodily functions as rest is for recovery and vitality. Being well-hydrated is necessary to maintain wellbeing, helps regulate body temperature and helps remove waste which if accumulated can cause discomfort and disrupt sleep.
The timing of fluid intake is also important. Excessive water consumption before bedtime can lead to awakenings. These interruptions can fragment sleep and decrease sleep if interruptions occur before reaching deep or REM sleep.
To walk the fine line between adequate hydration and sleep quality, consider these tips:
- Front-load your fluid intake. Aim to consume the majority of your daily water intake earlier in the day, tapering as you approach evening.
- Small sips. If you're thirsty in the hours before bed, take small sips to quench thirst rather than a full glass.
- Watch out for diuretics. Beverages like coffee and certain teas can increase urinary output and thus might best be enjoyed in moderation and earlier in the day.
- Listen to your body. Individual hydration needs can vary, so pay attention to your body's signals. If you're waking up thirsty, slightly increase your evening intake. Finding the right balance for your body is key.
Dietary Patterns and Sleep Disorders. Mediterranean and DASH.
Long-term dietary habits cast a profound impact on sleep health, with research increasingly drawing connections between what we eat and how well we sleep. Chronic conditions like insomnia and obstructive sleep apnea may be influenced by one's dietary patterns. High consumption of saturated fat and sugar, often present in processed and fast foods, has been associated with lighter, less restorative sleep, as well as greater difficulty maintaining sleep continuity.
Conversely, diets rich in fibre and whole foods encourage deeper sleep cycles and may prevent or manage sleep disorders. Specific nutrients play essential roles in supporting healthy sleep. Magnesium is found in leafy greens, nuts and seeds and acts as a natural relaxant. Complex carbohydrates, from whole grains for example, assist in the steady release of glucose into the bloodstream, which can promote blood sugar stability throughout the night.
Adopting a balanced dietary pattern, such as the Mediterranean or DASH diet, has been proven to be beneficial. This approach encourages an intake of diverse nutrients known to improve sleep and potentially ameliorate sleep disorders. By consuming a varied diet packed with fruits, vegetables, whole grains, and lean proteins, we can support our circadian rhythms and improve sleep efficiency and quality.
Behavioural Aspects of Diet and Sleep.
With sleep quality and issues; there is often a causality dilemma. What came first, the chicken or the egg? What came first, anxiety or poor sleep? In the instance of sleep, both aspects are entwined and equally as important as the other. Often, fixing one will help (if not entirely) ameliorate the other.
Sleep deprivation is not merely a matter of physical tiredness - it has profound ramifications for our behaviour and decision making capacities, particularly concerning our dietary choices. When we're sleep deprived, our body craves instant energy, often leading us towards high-calorie, sugary foods. This inclination occurs from hormonal shifts. Sleep loss increases the hunger hormone ghrelin, while diminishing leptin, the hormone that signals fullness. Consequently, our desire for calorie dense or sweet foods increases dramatically.
In a sleep-deprived state, the prefrontal cortex, which governs complex decision-making, becomes dulled, while the reward centres of the brain become more active. This imbalance triggers a greater desire for rewarding foods - those rich in simple carbs and sugar - which are often (if not always) less nutritious and rewarding. The instant gratification from these foods can become a learned behaviour, establishing a pattern of unhealthy eating as a quick fix to boost energy and mood.
Unfortunately, this unhealthy cycle reinforces itself. Sugary foods can lead to energy spikes and crashes, culminating in irregularities in eating and blood sugar levels, further disrupting sleep patterns. This spiral can be particularly challenging to escape from, as persistent sleep disruption can easily impair healthy food choices.
Breaking this cycle involves commitment and mindfulness. Prioritising adequate and consistent sleep, being conscious about food choices, and understanding the profound connection between sleep and diet. Together, balanced nutrition and good sleep hygiene can break the cycle of poor eating habits. Often improving your diet is an excellent first step in improving your sleep, where better quality sleep will then dramatically improve your food choices.
Meditation techniques have been found to be hugely beneficial in preparing one's mind for sleep and slowing down the digestive system by calming and slowing the sympathetic nervous system (fight or flight system) and activating parasympathetic (relax and repair) nervous system.
Meal timings and night-time cravings.
One of the cornerstones of quality sleep lies in the composition and timing of meals. A dinner balanced with lean protein, complex carbohydrates, and healthy fats can support steady blood sugar levels through the night, warding off disruptive hunger pangs. Timing is also important. Aim to have your evening meal at least three hours before bedtime to avoid indigestion or heartburn. Don’t be too strict about when you fall asleep after dinner. If it feels right to sleep after an hour, sleep after an hour. Paying attention to your sleep propensity peak ‘window’ takes precedence over sleep timing after a meal. Best practice is to lay on your left side if you are going to sleep within two hours of eating a large meal.
Portion control at night is also worth noting. A heavy meal can trigger metabolic processes that may disturb sleep. On the other hand, going to bed hungry can be just as counterproductive. If you wake up hungry, a light, nutrient-dense snack can provide the body with the fuel it needs without overtaxing the digestive system. Consider a slice of whole-grain toast with almond butter, a few fibrous crackers with cottage cheese, some nuts or a glass of warm milk.
Caffeine and alcohol are well-known sleep disruptors. Reducing intake, especially in the hours leading to bedtime, can significantly improve sleep quality. Opt instead for calming beverages like chamomile tea or warm milk, which can help soothe the body into a sleep-ready state.
Integration of Sleep Hygiene and Mindful Eating.
Sleep hygiene is a routine or habits that facilitates regular, restful sleep and creates an environment and routine that signals the body it's time to wind down and sleep. This includes maintaining a consistent sleep schedule, having a relaxing bedtime ritual, and a relaxing bedroom atmosphere that is cool, dark, and quiet.
Often, we need to get chores done or exercise after work and even after dinner which can disrupt sleep hygiene and good eating choices. Frequent exercise improves sleep, but depending on the fitness of the individual, vigorous activities can spike hormones such as cortisol and testosterone, leading to sugar cravings. In such cases, opt for foods rich in protein, fibre, magnesium and vitamin B6 as these are highly restorative, promote relaxation and help the body to produce melatonin.
Try to restrict caffeine and sugar intake after lunch but especially later in the day, to prevent overstimulation and sugar-induced energy spikes that may lead to restless nights. Foods like leafy greens, oatmeal, eggs, whole grains, nuts, seeds, fish and even dark chocolate are excellent choices to integrate with your sleep hygiene and evening routine as required.
This information is intended as a guide only and while most points mentioned will act as a helpful start towards establishing healthy eating habits for better sleep, diet is one of many factors that must be considered when addressing one's sleep health.
Similarly, the information stated above does not necessarily apply to people with special dietary requirements and considerations and therefore if in doubt, always seek the guidance from your doctor before making changes to your diet.