The relationship between sleep and diet is a complicated one. Recent news that fiber, sugar, and fat intake can cause sleep problems adds to a growing body of research connecting the two.
In a study published in the Journal of Clinical Sleep Medicine, researchers found that diets lower in fiber and higher in saturated fats and sugar are linked to less restful, more fragmented sleep with more frequent awakenings throughout the night. These diets also were associated with less time in slow-wave sleep, a highly restorative phase of sleep.
A vicious circle of sleep-affecting-diet, diet-affecting sleep occurs: Insufficient sleep spurs appetite, in part by altering hormones that regulate feelings of hunger and fullness. Short on sleep, our levels of the hunger-stimulating hormone ghrelin spike, while levels of leptin—a hormone that promotes feelings of fullness—drop.
As a result, when you're sleep deprived, you tend to consume more calories than your body needs. In addition to spiking overall appetite, insufficient sleep specifically increases your desire for fatty and sugary foods and also reduces your ability to withstand these food cravings (there's a strong scientific connection between insufficient and poor quality sleep and obesity).
What about the impact of diet on sleep? There's compelling evidence that both what we eat and when we eat influence our bodies' circadian rhythms. You might already know that eating heavily in the evening disrupts normal, restful sleep patterns. Recent research also found that insulin levels, which rise during and after meals and depend on the glycemic values of the foods we consume, may play an important role in resetting the body's circadian "clock." Keeping insulin levels moderate and healthy may contribute to a healthy sleep routine.
Other scientific evidence indicates that heavily processed, high-fat and high-sugar foods contribute to restless, poor-quality sleep as well as to prolonged sleep. Prolonged sleep may sound like a good thing, but it can throw off circadian rhythms and healthy sleep-wake cycles, putting you at risk for sleep disorders including insomnia.
The first step to happier sleep is to recognize that your eating and sleeping routines are inextricably connected. A sleep-friendly diet looks a lot like a healthy diet: full of whole, unprocessed foods, and plentiful in a variety of vegetables, fruits, legumes, whole grains, nuts, and lean proteins. Sleep-promoting foods include those rich in the minerals potassium, calcium, and magnesium and the amino acid tryptophan. And, as the recent study indicates, a high-fiber diet that is also low in sugar and saturated fats may protect you from restless sleep.
The bottom line? Eat healthy during the day, and you'll find yourself counting fewer sheep at night.