Table 1.

Human studies on sleep and plant-based diets.

Reference	Study Design	Participants	Sleep Quality Measurement	Diet-Related Variables	Main Outcomes
[130]	Cross-sectional study	390 overweight and obese women aged 18–48	The Pittsburgh Sleep Quality Index	FFQ was obtained, and plant-based dietary scores were calculated.	Unhealthful plant-based index was found to be associated with lower sleep quality. They failed to find an association between overall plant-based dietary scores and sleep quality.
[33]	Intervention study	Vegetarian group (n = 30) was fed a vegetarian diet and non-vegetarian group (n = 30) was fed a non-vegetarian diet for three months.	The Pittsburgh Sleep Quality Index	FFQ form containing fruit, vegetable, dairy product, fish, cereal, pulse, egg, meat, fat, sweet, beverage, and nut food groups.	The vegetarian group had significantly better sleep scale scores.
[104]	Cross-sectional study	2424 participants, 45 years and older	The Pittsburgh Sleep Quality Index	Semi-quantitative FFQ was obtained, and plant-based dietary scores were calculated.	A positive association between healthful plant-based index and overall plant-based index and sleep quality was found. A negative association between sleep quality and unhealthful plant-based index.
[131]	Cross-sectional study	1643 male and female adolescents aged between 11 and14 years	Pediatric Daytime Sleepiness Scale and self-reported sleep time	KIDMED and FFQ for Italians	Adolescents who had an early bedtime were found to eat more fruits and vegetables. Consumption of fruits and vegetables positively correlated with overall and weekday sleep duration.
[116]	Pilot intervention study	14 patients who have obstructive sleep apnea with a mean age of 59.1, BMI > 22	Epworth sleepiness scale	Participants had a whole-food, plant-based diet for 21 days.	A 21-day WFPB diet intervention decreased sleepiness during the day.
[132]	Cross-sectional study	230 diabetic women	The Pittsburgh Sleep Quality Index	FFQ was obtained, and plant-based dietary scores were calculated.	It was determined that individuals with high UPDIs had the worst sleep quality, and individuals with high HPDIs had the best sleep quality.
[133]	Pilot study	The 62 individuals who participated in the study were categorized as vegan, vegetarian, pescatarian, and omnivores according to the MEDAS result.	The Pittsburgh Sleep Quality Index	Mediterranean Diet Adherence Screener (MEDAS) questionnaire	Diet was not found to be effective for sleep quality.
[134]	Cross-sectional observational study	245 community physicians	Sleep-Related Impairment—short form	FFQ was obtained.	Each 1 SD increase in the plant-based diet score was associated with a 0.71-point decrease in the SRI.
[95]	Cross-sectional study	432 women aged 20–76	The Pittsburgh Sleep Quality Index	Alternate Mediterranean (aMed) diet score	A positive predictive association was found between adherence to the Mediterranean diet and sleep quality.

PDI: plant-based diet index; uPDI: unhealthy plant-based diet index; hPDI: healthy plant-based diet index; BMI: body mass index; KIDMED: Mediterranean diet quality index; FFQ: Food Frequency Questionnaire.