How physical activity and diet impact sleep in adolescents

Poor dietary habits, like consuming ultra-processed or nutrient-poor foods, negatively affect sleep.

Study: Association of Physical Activity and/or Diet with Sleep Quality and Duration in Adolescents: A Scoping Review. Image Credit: Fabio Principe / Shutterstock.com

A recent Nutrients study reviews the impact of physical activity (PA) and diet on the duration and quality of sleep among adolescents.

Why is sleep important?

Sleep is a fundamental biological need, particularly for adolescents, who are advised to sleep between eight and 10 hours every day. Despite these guidelines, most young adults only get about seven hours of sleep each night, with 11-30% of adolescents experiencing sleep disorders.

It is crucial to maintain an adequate and balanced diet that provides an adequate supply of nutrients and calories for various bodily processes and reducing the risk of chronic diseases. Thus, in addition to sleep, diet and PA are also essential for overall health.

Due to their role in maintaining health and well-being, investigating the potentially complex link between PA, diet, and sleep is imperative.

About the study

The current study reviewed published studies examining the association between diet and PA with the duration and quality of sleep in adolescents by searching several databases including PubMed, Scopus, Web of Science, and ERIC.

All reviewed studies evaluated PA and/or diet along with sleep, included a sample comprising adolescents between 11 and 18 years of age without health pathologies or alterations, used a quantitative research design, and were published in English or Spanish.

Studies that did not analyze the association between PA, diet, or both with sleep, focused only during the coronavirus disease 2019 (COVID-19) lockdown period, included systematic reviews and meta-analyses, were published prior to 2013, had incomplete text available, did not study the effects of PA or diet on sleep, or conducted an intervention were excluded from the analyses.

Study findings

Higher levels of PA were associated with better sleep duration and quality, as well as an earlier bedtime. For both males and females, higher moderate-to-vigorous physical activity (MVPA) was associated with increased sleep efficiency (SE).

The prevalence of insomnia was lower among boys with higher levels of PA, whereas this association was non-linear among girls. For some individuals, intense PA before bedtime interfered with sleep quality, which may be due to higher levels of circulating cortisol.

Several studies reported that sleep quality can be influenced by food choices and meal regularity. Sweets, spicy foods, and nutrient-poor foods were associated with poor sleep quality, whereas a diet rich in milk, fruits, vegetables, and low-energy foods was associated with a longer sleep duration.

The relationship between diet and sleep quality could be influenced by several factors including gender, PA, and screen time. Late dinner and bedtimes were also associated with poor sleep quality. More frequent consumption of salty biscuits, late dinner and bedtime habits, and less frequent strength training exercises was associated with shorter duration of sleep and poor sleep quality.

Importantly, the studies included in the current analysis examined the association of diet and PA with sleep duration and quality in isolation. Therefore, additional research is needed to study the potential additive effect of PA and diet on sleep.

Limitations

Only articles published in English or Spanish were considered in the current study, which could have led to the exclusion of other relevant research, thereby limiting the generalizability of the findings.

Future research is needed to establish the robustness of the findings, as only 13 studies were included in the review. Two of the reviewed studies investigated the association between diet, PA, and sleep; however, these studies only partially examined their interactions.

Importantly, the review findings lack causality and, as a result, are considered correlative, as the primary interest was to explore evidence on the combined association between diet and PA with sleep duration and quality in adolescents.

Conclusions

The study findings suggest that PA influences sleep quality and duration; however, additional research is needed, including studies that examine the sex-dependent relationship between insomnia and intensity of PA.

Dietary patterns can also significantly impact sleep. Specifically, a balanced diet low in ultra-processed foods and rich in fruits and vegetables is associated with longer sleep duration and better sleep quality.

Taken together, these results can be used to inform future policies to ultimately enhance adolescents’ quality of life through PA and/or diet and sleep.