Can A Plant-Based Diet Help You Sleep Better?

Key Takeaways: 

• Past studies have found that certain types of foods can help promote better sleep, but few look holistically at different types of diets. 
• A new study from China examined the link between plant-based diets and sleep quality. 
• Results suggested that plant-based diets may have a positive impact on chronic insomnia, with some differences across genders.

What we consume can have an impact on sleep quality. 

We know, for instance, that drinking alcohol is associated with poorer sleep outcomes (1), while foods rich in melatonin may support better sleep quality. (2) 

One drawback of these existing studies is that they tend to focus on the impact of specific foods and beverages on sleep, rather than looking holistically at dietary patterns. Existing research also doesn’t take the quality of diet into account. 

However, these shortcomings are addressed in a new study published in the European Journal of Clinical Nutrition, which examined the relationship between insomnia and plant-based diets. The research — also referred to as the Tzu Chi Health Study — additionally explored whether the quality of diet had any impact on sleep quality. 

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How Dietary Patterns Affect Sleep Quality

The Tzu Chi Health Study is a longitudinal cohort study that recruited 5,821 eligible participants between 2007 to 2009 and followed them until 2018. All participants were screened to ensure that they were over the age of 20 at the time of recruitment, did not have a baseline insomnia diagnosis, had complete dietary data, and did not report extreme energy intake.

The participants were then separated into two categories: vegetarians — defined as people who hadn’t consumed any meat or seafood for at least a year — and non-vegetarians. 

While adherence to diet was self-reported, researchers used Taiwan’s National Health Insurance (NHI) program database, which contains medical claims of all inpatient and outpatient services for nearly 99% of Taiwan’s residents, to identify participants who were prescribed sleep-related medication for chronic insomnia. (3)

The results of the study suggested that a vegetarian diet was associated with a lower risk of insomnia — independent of age, BMI, volunteer status, anxiety, depression, and menopause status in females. 

However, the impact of a vegetarian diet on insomnia appeared to differ across genders. Specifically, the hazard ratios (HR) — which is a measure of how often a particular event happens in one group compared to another — were 0.47 for male participants and 0.71 for female participants. 

In other words, male vegetarians had about 53% lower risk and female vegetarians had about 29% lower risk of developing insomnia compared to their non-vegetarian counterparts.

Does The Quality of The Diet Matter? 

The Tzu Chi Health Study also measured the relationship between quality of diet and insomnia.

To do this, the researchers developed a scoring system — called the healthful plant-based index (hPDI) — to assess how strictly participants adhered to their vegetarian diets. 

This system was created based on methodology from an existing study, but a few adjustments were made to reflect an Asian diet. (4) For example, the scoring system was adapted to incorporate more soy products, which are common in Asian diets. 

The analysis of these self-reported assessments showed more significant discrepancies across gender. Among male participants who had the highest hPDI scores — meaning the ones who most closely followed the healthy plant-based diet — they found a 50% lower risk of insomnia compared to male participants with low hPDI scores. 

However, the results for female participants showed no observable links between their hPDI scores and their risk of insomnia. 

The Implications of This Study

Insomnia is known to have a negative impact on mental health, leading to side effects such as reduced mental acuity, productivity, and mood. Insomnia also has negative implications for physical health, leading to increased risk of heart disease, high blood pressure, obesity, stroke, and infections. (5) 

Many people who experience insomnia are prescribed sleep medication. According to the Centers for Disease Control and Prevention (CDC), 8.4% of adults used sleep medication every day or most days in the past 30 days to help them fall or stay asleep in 2020. These medications often come with side effects and risks of complications, such as digestive issues, headaches, muscle weakness, and withdrawal symptoms. (6)

With the findings of the Tzu Chi Health Study — which is one of the few longitudinal studies investigating the associations between plant-based dietary patterns and insomnia — there’s an opportunity for healthcare providers to consider more holistic, diet-focused approaches for patients who are struggling with insomnia.

Looking Forward: Future Studies Should Diversify Population Groups and Diets Explored

According to the researchers of the Tzu Chi Health Study, there’s an opportunity to continue exploring the link between diverse diets and sleep quality across various population groups.  

They also noted that, in their research, they only studied the link between plant-based diets and its impact on chronic insomnia. It may be beneficial for future studies to explore the association between certain diets and more mild forms of insomnia that don’t require medication.