Research & Your Health is a series of articles written in accessible, everyday language, focused on the latest scientific research of natural health products.
On May 20, 2016
Background: There is a large body of research suggesting that reduced sleep duration has been linked to negative health behaviours, such as unhealthy food consumption and weight gain, suggesting that sleep restriction may affect dietary intake. Interestingly, recent research has also indicated that diet may affect sleep as well. However, very few studies have properly assessed this potential causal relationship.
Objective: The objective of this study was to assess whether sleep quality was different following a controlled or ad libitum (i.e. self-administered and based on participant preference) diet, and to see whether the contents of the ad libitum diet affected sleep.
Methods: 26 healthy adults (13 men and 13 women aged 30-45) took part in a six-day inpatient study. Participants spent nine hours in bed each night, and were provided with a controlled diet for the first four days, with the final two days as an ad libitum diet. During the controlled-diet phase, participants were provided with individualized meals (based on energy requirement calculations) at specific times during the day, with specific macronutrient composition (approximately 31 per cent, 53 per cent, and 17 per cent energy from fat, carbohydrates, and protein, respectively). On the remaining two days, participants were provided with $25 to buy their own food to eat in the lab, with no restrictions on when participants ate or the macronutrient content of the meals. The nutritional composition of the food was analyzed before the participants consumed their meals during the ad libitum diet days. Sleep quality and content was assessed on night three (after the controlled diet) and night five (after the ad libitum diet).
Results: Night five (measurements taken after the ad libitum diet) was associated with reduced slow wave sleep (SWS, the state of sleep where the body is in a deep and restful sleep state) and delayed time to falling asleep. Total sleep time, and time spent in sleep stages and rapid eye movement (REM, deep sleep where dreaming occurs) were not different between nights three and five. While diet did not predict total sleep time on night five, increased fibre consumption was related to reduced time in stage one sleep and greater time in SWS. On the other hand, increased saturated fat consumption was related to reduced time in SWS. Percentage of energy from sugar consumption and non-sugar/non-fibre carbohydrate consumption were all related to increased sleep arousal on night five.
Conclusion: More saturated fat and less fibre intake was associated with less and lighter sleep, and more sugar and non-sugar/non-fibre carbohydrate consumption was also related to less restful sleep, in a laboratory study with healthy adults.
Findings and Perspectives: This study points to the importance of diet on sleep quality and length, particularly in regards to saturated fat, fibre, and carbohydrate intake. More research should be done outside of the laboratory to understand the effects of diet on sleep in the "real world," potentially with larger sample sizes.
St-Onge, M. P., Roberts, A., Shechter, A., & Choudhury, A. R. Journal of Clinical Sleep Medicine (2016): 12:1