While high fiber foods have long been touted as sleep aids, we now know that eating more fiber can lead to deeper, more restful sleep. Columbia University published a study in the Journal of Clinical Sleep Medicine showing that those with more fiber in their diets were able to spend more time in the dreamless, restorative slow-wave sleep phase.
This smaller study looked at 26 adults of normal weight, who reported sleeping seven to nine hours per night. Participants completed 2 phases of 5 days each. Each phase consisted of 4 days with a controlled diet, and 1 day where foods were self-selected. What they found was that after a day of ad-libitum eating, subjects had less slow-wave sleep and sleep took longer to achieve.
The other factors that this study controlled for were the amounts of sugar and saturated fat in the diet. When a greater percentage of saturated fat was in the diet, participants had a decreased amount of slow wave sleep. Those who consumed larger amounts of sugar and other carbohydrates were found to wake more frequently through the night.
It was found that even a single day of diet modification could impact sleep quality, either positively or negatively, so clients can see noticeably fast improvements in sleep. This was the most surprising facet of the study, as noted by principal investigator Marie-Pierre St-Onge, who is assistant professor in the department of medicine and Institute of Human Nutrition at Columbia University Medical Center in New York.
This new information may partially explain the phenomenon among individuals who choose a low- or zero- carbohydrate diet, as many of them report decreased amount and quality of sleep. Since they tend to increase the amount of saturated fat in place of other foods, they may consider adding more fiber-rich vegetables instead. While saturated fat has somewhat been absolved of its role in heart disease and other issues, clients may still need to moderate this intake.
Vegetarians who choose carbohydrate-rich foods may also face these sleep issues, since their diets can be heavy in pastas and breads, as well as fruits. Working with vegetarian clients to plan meals that decrease the carbohydrates in general, and especially sugar-heavy foods may offer benefits to those who are complaining of sleep issues, especially when sweeter foods are chosen away from bedtimes.
It’s possible that the increased amount of fiber intake positively impacts hormone balance, and this may contribute to the improved sleep quality. Many of the current studies on the link between fiber and hormones focus on the reproductive and weight managing aspects of this type of food, though the ideally tight homeostasis of the endocrine system can lead us to think there may be benefits to sleep quality as well.
Future studies are planned on these issues. This current evidence is promising though, considering that poor sleep has been shown as a contributing factor in many conditions such as elevated stress hormones, hypertension, cardiovascular disease, and obesity.