The Mediterranean Diet may be able to improve your sleep

In a recent review published in Nutrients, researchers review the associations between following a Mediterranean diet (MD) and features of sleep such as sleep duration, insomnia, daytime sleepiness, and overall sleep quality.

Study: Mediterranean diet and sleep features: a systematic review of current evidence. Image Credit: PeopleImages.com – Yuri A / Shutterstock.com

MD as a healthy, palatable, and environmentally sustainable diet

MD is rich in plant-derived food items such as whole grains, fruit, vegetables, legumes, and nuts, and has been established as easy to adopt across non-Mediterranean cultures. Numerous studies have shown that following MD can reduce the risk of some cancers, neurodegenerative diseases, and cardiometabolic disorders.

Since MD adherence may be associated with other healthy habits and aspects of one’s lifestyle, it may also improve the quality and other features of sleep. Following a healthy diet and sleeping well could reduce the risk of chronic non-communicable diseases.

To identify relevant papers, researchers conducted a systematic search across the EMBASE and PubMed databases, including all papers published until January 2023. Observational studies and those including people over 18 years of age were included in the analysis.

Studies were excluded if they were conducted on pregnant women, children and adolescents, or people suffering from late-stage degenerative conditions. This led to a total of 23 publications for the review.

The benefits of MD on sleep

Thirteen of the reviewed studies were conducted on people living in France, Greece, Spain, and Cyprus. Several articles found evidence that high levels of adherence to MD were positively associated with better sleep quality and long sleep duration.

Comparatively, adherence to MD was negatively associated with risk of sleep duration changes, symptoms of insomnia, and daytime sleepiness. Notably, some studies found significant associations for one sex but not the other, whereas others found no relationship between sleep and MD adherence.

Significant associations between sleep quality and MD adherence were also reported from countries outside of the Mediterranean region, thus suggesting that there may be biological mechanisms that lead to the observed relationship. These studies found positive associations between MD adherence, sleep quality, and healthy sleep timings, as well as negative associations between MD adherence and daytime sleepiness, disturbed sleep, and insomnia symptoms.

Eighteen of the included studies were conducted on healthy adults, whereas the remaining studies included people with health conditions such as breast cancer, multiple sclerosis (MS), obstructive sleep apnea, and rheumatoid arthritis. The findings from these studies suggest that individuals living with these conditions may also have better sleep if they follow MD.

For example, women with breast cancer and people with sleep apnea were less likely to suffer from insomnia if they adhered to MD, whereas individuals with MS who followed MD reported less disturbed sleep.

Is there a causal impact?

Overall, the study findings overwhelmingly found that adhering to MD was associated with better sleep outcomes. This relationship could be due to the beneficial effect of following an MD on brain health.

MD is rich in antioxidant vitamins and polyphenols, which could reduce inflammation. While MD is rich in fat and carbohydrates, these are healthy unsaturated fatty acids that are found in olive oil and fish.

People who follow MD often opt for home cooking instead of ready-to-eat items and snacks, thereby reducing their consumption of long-chain saturated fatty acids and hydrogenated trans fats. Plant-based diets are also rich in minerals like magnesium and zinc, which can improve sleep regulation.

Study limitations

While these findings are compelling, consistent across multiple studies, and drawn from large cohorts, the studies included in the review have some limitations. For example, since all the studies were observational and most were cross-sectional, they did not allow for causal inference.

Furthermore, the information regarding dietary adherence and sleep quality was self-reported and could be affected by social desirability and recall biases. Finally, meta-analyses could not be conducted in the review as there was great variation in the tools and instruments used to collect data across the 23 studies.

Conclusions

MD can be a promising intervention to improve sleep quality in people living outside Mediterranean regions and those diagnosed with various health conditions. Nevertheless, future studies are needed to assess the causal impact of following an MD on sleep outcomes.