Among the pillars of good health are two that we’ve heard all our lives: Eat a nutritionally sound diet and get enough sleep. We may be all too aware of their individual importance, but it’s likely that we think less about how these two vital aspects of well-being interact with each other.
According to sleep experts, the quality and quantity of the foods we eat have an impact on the quality and quantity of our sleep. In fact, several common dietary habits lead to poorer sleep—from consuming too much caffeine and added sugar, to not getting enough micronutrients. And, conversely, getting enough sleep goes hand-in-hand with improved health.
So, if you’re on the hunt for a better night’s rest, here's what you need to know about diets and sleep, according to studies and health experts.
Sleep and overeating
How do you feel after you eat too much? Most people become lethargic and drowsy, slipping into the phenomenon we often describe as a “food coma.” But while we may feel like a snooze is in order, eating excessively is associated with poorer sleep quality, according to a study published in the Journal of the American Heart Association (JAHA).
The study followed a cohort of 495 women, aged 20-76. Researchers monitored their eating habits, sleep quality, and how quickly it took them to fall asleep at night, and found that trouble sleeping at night was associated with several factors, including the quantity of food consumed.
Higher rates of sleep-onset latency were associated with those who had higher intakes of food by weight, with those who ate the most food often found themselves taking longer than 60 minutes to settle down at night. Researchers didn’t establish causality as part of the study, but they did hypothesize that excessive food consumption may lead to gastrointestinal discomfort, which may disrupt sleep or make it harder to fall asleep.
While eating too much may just be linked to individual cases of poor sleep for some, it can lead to more serious effects for others. Researchers also found that higher intakes of food were found to be associated with insomnia presence and severity.
If you want to learn more, check out 15 common sleep myths at MDLinx.
Sleep, caffeine, and sugar
Perhaps unsurprisingly to coffee and sweet treat lovers, the aforementioned JAHA study drew a similar link between poorer sleep quality and consumption of caffeine and sugar.
The highest length of sleep-onset latency in the study (more than 60 minutes) was associated with higher caffeine intake (along with food by weight), compared with the lowest rate (fewer than 15 minutes). The highest levels of insomnia severity were also associated with higher caffeine intake.
Additionally, poorer sleep quality (as measured using the Pittsburgh Sleep Quality Index) was found to align with higher intakes of caffeine and added sugars. The results were similar to previous studies, which found intake of confectionery and sugary beverages tend to correlate with poor sleep quality.
It makes sense to avoid added sugars and caffeine before bed, but coffee brings health benefits that make it worth keeping in your diet—as long as you drink it several hours before turning in for the night.
Sleep, unsaturated fats, and dairy
The JAHA study also took a closer look at how consuming dairy products and foods high in unsaturated fats affect sleep. Researchers observed an inverse association between those who have trouble sleeping and dairy intake—ie, poorer sleep quality was associated with a lower level of dairy consumption. They also found that not consuming enough dairy products appeared to be associated with having trouble getting to sleep. There may be scientific wisdom behind that warm glass of milk after all.
The authors also wrote that "Contrary to our hypothesis, sleep quality was inversely related to total fat intake and not associated with saturated fat intake. This is divergent from studies on sleep duration and architecture, which find that shorter and lighter sleep relate to greater total fat and saturated fat intakes, respectively.”
They pointed out that good sleep in the study sample also correlated with higher unsaturated fat intake which can reduce risks of cardiovascular disease. That suggests that there may be a relationship between higher sleep quality and a healthier dietary fatty acid profile.
Sleep and whole grains
While they didn’t write at length on the subject, the authors of the JAHA study found that lower intakes of whole grains were associated with worse quality sleep and more trouble getting to sleep.
This observation is corroborated in an article reviewed by Kimberly Truong, MD, a physician who specializes in sleep. According to the article, the DASH diet (Dietary Approach to Stop Hypertension) may help improve sleep. It focuses on intakes of whole foods, particularly those high in fiber, potassium, and magnesium. While the diet is designed to help patients reduce their blood pressure, research indicates that it tends to help people sleep better, too.
Sleep and micronutrients
The article also points to micronutrient intake as an influencer of sleep quality, suggesting that deficits of calcium, magnesium, and vitamins A, C, D, E, and K, may affect the way we slumber.
This was illustrated by an analysis published in Nutrients, which examined the sleep patterns and dietary habits of a cohort of 26,211 individuals from 2005-2016, with a specific focus on micronutrients. Researchers found that those who reported fewer hours of sleep tended to have lower intakes of calcium, magnesium, vitamin D, and vitamin K.
Researchers noted that many of these nutrients have demonstrated roles in sleep regulation. For example, vitamin D receptors have been identified in regions of the brain that regulate sleep, and some research has suggested that it plays a role in regulating genes involved in mediating circadian rhythms.
Eat well, sleep well, live well
While scientists may not have established all the mechanisms involved, the evidence is compelling: What we eat impacts how well and how long we sleep. The authors of the JAHA study point out that most research has linked overall sleep quality to the consumption of certain nutrients and foods that are associated with disease risk.
If you want to improve your sleep, you can start by learning which foods to avoid before bed. And chances are, if you start eating healthier, you’ll end up sleeping better at night.
Read more about the consequences of sleep deprivation on medical professionals at MDLinx.