Study Finds Consuming More Fruits and Vegetables Can Improve Sleep
New research from Erica Jansen
Research Assistant Professor of Nutritional Sciences
A new study published in Sleep Health Journal found increasing consumption of fruits and vegetables improved insomnia-related symptoms in young adults, especially young women. According to the Office on Women’s Health within the US Department of Health and Human Services, approximately one in four women experience insomnia. Findings from the research highlight dietary improvement as another therapeutic recommendation for women experiencing insomnia.
Erica Jansen, research assistant professor of Nutritional Sciences at the University of Michigan School of Public health and lead author of the study, discusses the findings.
What does previous research suggest about the relationship between fruit and vegetable consumption and sleep?
Previous research has shown that fruit and vegetable intake is associated with longer sleep duration and higher sleep quality, although most of that research is cross-sectional, so it is impossible to determine which came first (and it’s likely that there are truly bidirectional associations).
The unique aspect of this study is that we were able to see that as fruit and vegetable intake changed, insomnia-related sleep characteristics also changed. We still cannot rule out that sleep characteristics changed first, which in turn caused a change in fruit and vegetable intake, but since the participants were part of a trial to increase fruit and vegetable intake, it is more likely the other way around. The participants were not told to change anything about their sleep habits.
What were the most significant findings of the study?
Within the study population of young adults who were overall low consumers of fruits and vegetables, meaning they reported eating less than five servings per day, there was a pretty high prevalence of chronic insomnia symptoms, with over one-third reporting difficulties with falling asleep or maintaining sleep at least three times per week for three months or longer.
In particular, women who were able to increase their fruit and vegetable consumption by three or more servings over a three-month period were more than twice as likely to experience an improvement in these insomnia symptoms. We did not see differences in sleep duration over this time, but this wasn’t surprising to us since sleep duration was self-reported and because bedtimes and wake times are often largely determined by work, school schedules, and social pressures and may not be as responsive to dietary changes. Associations between dietary change and sleep change were not as strong among men.
Do you have an idea of why females showed more improvements than males in the study?
This study was not designed to test mechanisms, so we really aren’t sure. However, it was not that surprising to us that findings differed by sex, because a lot of studies have shown different associations between sleep and diet in females compared to males. We also know that females report a much higher prevalence of insomnia than men, so it’s possible that insomnia symptoms fluctuate more in females and that these symptoms are more responsive to environmental factors including diet.
One of the strengths of our study was that we had over 300 men participate (1,165 total participants in the study), which gave us enough statistical power to examine gender differences. This is unique as young men can be hard to recruit in studies such as this.
Were there any findings that surprised you?
Overall we were very excited to see that a fairly simple dietary intervention, such as encouraging an increase in fruit and vegetable consumption, could make an impact on sleep. Future studies to hone in on whether particular types of fruits or vegetables are driving the associations would be really interesting and clinically useful.
What would you like people to take away from this research?
One of the key takeaways is that the potential benefits of increasing fruit and vegetable consumption extends beyond weight and metabolic-related outcomes. The goal of the original fruit and vegetable trial was not centered on weight loss and participants were not advised to count calories or to focus in any way on their weight. So it’s great to see that when people add in more fruits and vegetables, they may experience some tangible improvements in sleep. Further, we know from other literature that improving sleep improves overall quality of life and many other health outcomes, so the benefits likely extend beyond the sleep changes. We do need to bear in mind that this study population was a group of young adults with low consumption of fruits and vegetables, so these associations may not extend to populations who already have higher dietary quality.
From a sleep clinician perspective, these findings are useful because the advice to eat more fruits and vegetables could be incorporated into other sleep hygiene principles, which include things like maintaining a consistent bedtime and rise time, eliminating screens prior to going to bed, sleeping in a dark, cool environment, and not consuming caffeine or alcohol before bed.
Dr. Gwen Alexander from the Henry Ford Health System was the senior author and principal investigator of the MENU GenY study, a randomized intervention among young adults. Other authors included Ruicong She from Henry Ford Health System and Margaret Rukstalis from University of South Carolina Medical School.