With sleeping pills getting bad press these days, the race is on to find more nonpharmacologic, alternative treatments for insomnia. One area of interest is diet and nutrition. Are there foods that could help us sleep?
The evidence for a relationship between food and sleep is mixed, say authors that reviewed 21 studies on the topic. But a new randomized controlled study of the effects of diet on sleep suggests that foods high in fiber, saturated fat, and sugar may significantly affect the quality of our sleep.
Measuring Sleep Depth and Duration
Twenty-six people (none with insomnia) participated in the study. All were normal sleepers, averaging 7 to 9 hours of a night.
The study was conducted in two 6-day periods. During one of these periods, the participants were allowed to sleep up to 9 hours a night every night. During the other 6-day period, their sleep was restricted to 4 hours a night for the first 4 nights, followed by a night of unrestricted sleep.
Participants underwent polysomnography—the test recording brain waves and the depth and nature of sleep—every night. Investigators kept track of variables such as total sleep time, sleep onset latency, number of arousals, and deep sleep.
A Controlled Diet
On the first 4 days of each 6-day period, participants were given enough food to meet their need for calories, but the type of food was controlled. On days of the controlled diet, participants were given food in which
- 31% of the energy came from fat ( 7.5% from saturated fat),
- 53% of the energy came from carbohydrates, and
- 17% of the energy came from protein.
On days 5 and 6, study participants could eat the foods they wanted as long as the nutrient content could be readily determined.
Participants underwent other testing as well, including a glucose tolerance test and a blood test.
Fiber, Saturated Fat, and Sugar Alter Sleep Quality
Study results showed that participants consumed significantly more calories on the day after 4 nights of restricted sleep (a day when they could eat as much as they wanted) than during the period when they were allowed to sleep as much as they normally slept. This confirms the results of other research showing that people who don’t get enough sleep tend to eat more and gain weight.
But after statistical analysis, investigators identified a few dietary variables that were associated with changes in sleep quality:
- Eating more foods high in fiber was associated with less stage 1 sleep (the lightest stage) and more slow wave sleep (or deep sleep). Foods high in fiber include fruit with skin; whole grains; legumes, nuts, and seeds; and vegetables such as artichokes, peas, and broccoli.
- Eating more foods high in saturated fat predicted less deep sleep. Foods high in saturated fat include meat, cheese, and other dairy products.
- Eating more foods high in sugar and non-sugar/non-fiber carbohydrates was associated with more nighttime wake-ups. Foods high in sugar and starch include fruit juice, pop, white rice, pasta, potatoes.
The study has limitations, including its small size and short duration. Also, whether the results would be the same for people with insomnia is unknown.
But the implications of the study reinforce what we hear elsewhere. For health reasons, we’re told to cut down on meat, dairy, and processed foods, and increase our intake of fruit and vegetables. Now there’s another reason to do that: it may improve the quality of our sleep.