Sleep and nutrition are closely linked. What you eat, when you eat, and even what nutritional supplements you take can all play a role in how well you sleep.
Food and sleep: how what you eat affects your sleep
What does science say about this? Here we dive deeper into the influence of nutrition on sleep based on recent insights and research. What you can already take away is that, as with sleep, regularity is also a golden rule for nutrition.
Eat and sleep according to a certain rhythm!
We have talked a number of times about our biological clock. A lot in our body works according to that biorhythm. In fact, all the cells in our body work according to a certain rhythm.
The gut is sometimes called your second brain. A particularly beautiful microbiome that connects our intestinal flora to our brain via the vagus nerve, among other things. The complex system is, according to neurologist Ingrid Declercq, sensitive to melatonin, the neurohormone that triggers your sleep system.
Our biorhythms are regularly readjusted by certain “zeitgebers,” or factors that set your clock back “truer. Environmental factors such as light and nutrition play an important role here. Our sense of hunger and satiety is controlled, among other things, by our biological clock.
Digesting food is also regulated thanks to cells in the liver, stomach, pancreas and in your intestinal system that act on these rhythms. This domain is called “chrononutrition,” and attention to it is growing rapidly among sleep researchers.
Fact or fiction?
Do proteins: have a positive impact on your sleep?
Research shows that people with better sleep quality tend to have more protein in their diet writes Merijn Van de Laar, among others. Higher protein intake is associated with better sleep quality, especially in overweight people. For example, a high-protein diet for four weeks led to improved sleep quality according to research by Zhou et al., in 2016. Yet there are conflicting results: another study found that more protein was actually associated with shorter sleep duration (Santana et al., 2012). It seems that a balance in this is important.
Inge Declercq writes about tryptophan foods in her book “The Power of Sleep. She does point out that they are certainly not miracle drugs that can solve insomnia, for example. They are good for your body and also have a low glycemic index. So consider: fatty fish, poultry, avocado, legumes, eggs, dairy products like (cheeses, milk, cottage cheese and yogurt), seeds and nuts.
Tryptophan is a substance that you cannot make yourself; you must absorb it through food. Per day, you need about 280 mg of tryptophan. It is a building block for serotonin, which is converted into vitamin B3. A derivative of tryptophan is melatonin. Inge Declercq also says in the book that studies show that taking tryptophan in the evening is conducive to falling asleep. Subjective sleep quality improves and waking during the night decreases.
Fats and carbohydrates: less is more?
People who eat more fats often experience poorer sleep quality is shown in research by Sutanto et al, from 2020. It also appears that a diet rich in carbohydrates may interfere with deep sleep, a crucial component of nighttime recovery (Phillips, 1975). However, research in this area is limited and sometimes methodologically weak. For now, less fat and moderate carbohydrates seem beneficial for better sleep.
Lamb, pork and beef in themselves do contain a lot of protein but at the same time they contain a lot of saturated fats. These need to be digested and therefore people wake up more often when you eat meat late.
Eating times and Sleep
Does it matter to your sleep what time you eat?
Studies show that eating late, especially shortly before bedtime, can lead to poorer sleep quality. This may be because late meals activate the body when it should be preparing for rest. Eating is at odds with sleeping because we are not made to digest our food at night.
People who eat fatty and or sugary meals, such as fast food, late at night tend to sleep worse. As your bedtime approaches, it is best not to eat more, especially fatty and sugary foods. Your blood sugar and cortisol levels will go up, whereas to sleep well it is best to keep these as low as possible. Better choose tryptophan-rich foods and limit the amount.
What if you’re still hungry?
Still hungry right before bed? Then pay attention to the glycemic index (GI) of foods. This indicates the amount of sugars (glucose) in your blood when you eat certain foods. The lower the GI value, the less insulin is needed to process sugar.
Note this does not mean that you have to omit sugars (or carbohydrates) from your diet in the evening, for example. Until four hours before you go to bed, you may feel free to eat these but best foods with a low GI such as: legumes, fruits, vegetables, oatmeal, unsalted nuts or low-fat yogurt.
So avoid soda, candy, ripe bananas, grapes, honey, breakfast cereals, white rice or potatoes. The GI of the latter is ideal for daytime because that’s when you need a lot of energy.
Fancy a sleep cocktail to help you fall asleep fast? I think you should definitely read the book “the power of sleep” for yourself, but this sleep cocktail by Inge Declercq gets a little podium:
What you need. Half a cup of Greek yogurt, sugar-free almond milk and sour cherry juice or frozen sour cherries. Mix these ingredients together into a cocktail and add a little cinnamon or maple syrup for added sweetness. Santé and sleep well!
What does research on nutrition and sleep say?
Milk, kiwis and more: myth or truth?
The effects of foods such as milk, kiwifruit and sour cherry juice on sleep have been much debated. Research shows that milk (tryptophan-rich) can have a small positive effect on sleep quality, but the effects are modest (Komada et al., 2020).
Kiwifruit also appears to improve sleep quality, but available research is limited and sponsored by stakeholders (Lin et al., 2011).
Sour cherry juice may slightly prolong sleep duration, but again this is based on small-scale studies. And you should already drink almost half a liter, at least 2h before bedtime.
Supplements such as tryptophan and vitamin D may have modest positive effects on sleep (Sutanto et al., 2022; Chan & Lo, 2022). Yet caution is advised: effectiveness is often limited and some supplements may have side effects. Melatonin, for example, is often misused and may exacerbate sleep problems in some cases (Sateia, 2017).
Conclusion – Nutrition and sleep
Although research on the relationship between nutrition and sleep is still in its infancy, there are some important insights:
1. Protein seems beneficial: A higher proportion of protein in the diet may contribute to better sleep quality.
2. Avoid excessive fats and carbohydrates: These are associated with poorer sleep.
3. Pay attention to the timing of your meals: Prefer not to eat too late in the evening, and avoid heavy, high-fat meals right before bedtime.
4. Be critical with supplements: Although some supplements such as tryptophan show potency, more research is needed to confirm their effectiveness.
5. Small benefits of specific foods: Milk and perhaps kiwifruit can help, but don’t expect miracles.
Nutrition and sleep remain complex topics. For now, a balanced diet with attention to timing seems to be the key to better sleep. And as always, consult a doctor or dietitian if you want to drastically alter your diet or try supplements.
Sources:
The insights in this article are based on recent scientific research, as described by Merijn van de Laar, PhD, and other published studies and “the power of sleep” a super recommended book by Inge Declercq.
