A diet low in fiber and high in saturated fat and sugar is associated with lighter, less restorative sleep with more arousals, a new study has found.
The researchers suggest that adjusting diet to include more fiber and less saturated fat and sugar may be useful in the management of sleep disorders.
The study, published in the January issue of the Journal of Clinical Sleep Medicine, was led by Marie-Pierre St-Onge, PhD, Institute of Human Nutrition at Columbia University Medical Center, New York.
"We found that sleep quality appears to be affected by what we eat, with fiber and saturated fat particularly important factors," she told Medscape Medical News.
"Our message is that a diet high in fiber and low in saturated fat and sugar is associated with better sleep patterns. For a good night's sleep we recommend increasing fruits, vegetables, and whole grains and eating less processed foods. That is a healthy diet in many other ways too particularly in terms of cardiovascular risk, so this is another reason to eat the right things."
For the study, 26 normal-weight adults aged 30 to 45 years who did not have any sleep issues were monitored for 5 nights in a sleep lab, spending 9 hours in bed each night from 10 pm to 7 am. Objective sleep data were gathered nightly by polysomnography.
During the first 4 days, participants consumed a controlled diet; on day 5, food intake was self-selected. Linear regression was used to determine relations between daytime food intake and nighttime sleep on day 5.
Results showed that sleep duration did not differ after the days of controlled feeding vs the day of self-selected food intake. However, the quality of sleep was different, with less of the deep slow-wave sleep (P = .043) and longer times taken to get to sleep (P = .008) after the day of free eating.
Analysis of the foods eaten showed that greater fiber intake predicted less stage 1 (very light) sleep (P = .0198) and more slow-wave sleep (P = .0286).
Percentage of energy from saturated fat predicted less slow-wave sleep (P = .0422), and higher percentages of energy from sugar and other carbohydrates were associated with more arousals (P = .0320 and.0481, respectively).
"These results are important since there is currently very little information on the role of diet on sleep, and dietary recommendations for lifestyle management of sleep disorders are lacking," the researchers state.
Dr St-Onge noted that the original purpose of the study was to investigate whether sleep is a causal factor in the development of obesity, with participants also undergoing a separate phase of much shorter sleep durations (just 4 hours per night), and then analyzing differences in food intake following shorter and longer duration sleep times.
"Results from that part of the study showed that people tend to overeat when sleep restricted and they particularly increase their intake of fat," she explained. "We were also interested to see if the reverse is true — that if what you eat affects how well you sleep, and the current results suggest that this does indeed seem to be the case."
She said the two sets of results together paint a picture of a vicious cycle. "If sleep is restricted you are setting yourself up for a poor diet with increased fat and sugar and that in turn will further adversely affect sleep. So it becomes a perpetual cycle."
She pointed out, however, that the participants in the current study were all healthy sleepers. "We did not include people who had difficulty sleeping in this study. But we would like to study this group next and see if their sleep problems improve with better diets."
The researchers did not study the mechanism behind these effects, but Dr St-Onge suggested that it could involve effects on circadian systems. "High carbohydrate intake delays circadian rhythms and reduces melatonin secretion, which would delay sleep onset. Hormones also come into play, as there is a heightened awareness of the reward value of food when sleep restricted. And when we are tired our decision making is not so disciplined, so we are more likely to give in to temptation to eat unhealthy food," she said.
The researchers acknowledge that further studies are needed to confirm their results. But if diet is found to play a causal role in sleep quality, then diet-based recommendations may be warranted for those who have sleep disorders, including insomnia, short sleep duration, and poor overall sleep quality.
They add that these findings could also have implications for some dietary-based therapies, such as the high-fat, low-carbohydrate ketogenic diet that has been promoted for several neurologic disorders.
"Increasing our understanding of the impact of dietary intake on nocturnal sleep will have many important and practical ramifications for public health," they conclude.
This study was funded by National Institutes of Health grants and by the National Center for Advancing Translational Sciences, National Institutes of Health, formerly the National Center for Research Resources.
J Clin Sleep Med. 2016;12:19-24. Abstract
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Cite this: Healthy Diet May Improve Sleep Quality - Medscape - Jan 22, 2016.