Can food choices affect your sleep? Researchers of a new study investigated how protein intake impacts sleep quality and identified the superior protein source that could improve sleep.

According to the results of the study published in the European Journal of Clinical Nutrition, there was no significant association between total protein intake and sleep quality. However, while comparing animal protein with plant protein, researchers saw that the total plant protein intake was positively associated with better sleep.

The results were based on an observational study conducted in three U.S. cohorts: Nurses' Health Study (NHS), NHS2, and Health Professionals Follow-up Study (HPFS). The dietary intake of the participants was estimated every four years using food frequency questionnaires. To measure sleep quality, researchers used the Pittsburgh Sleep Quality Index and adapted versions of the same.

"Overall, intakes of processed red meat and poultry were associated with worse sleep quality, whereas no or positive associations were observed for dairy and fish protein. Our results suggest that plants as a source of protein may be associated with better sleep quality than animal sources of protein. Further studies are warranted to validate our findings," the researchers wrote.

Out of 98,134 participants, around 5-6% of participants used sleep medications regularly. Researchers noted that sleep apnea was more common among those who ate a lot of protein, especially men.

People with better sleep quality typically had lower BMI values, higher physical activity, better diet quality, higher consumption of alcohol, and fewer pre-existing health conditions. Those who ate more animal protein tended to have more weight, were less active, and had more health problems compared to those who ate more plant protein.

"The most important finding is the fact that not the amount of protein seems to be of importance but the type of protein might make a difference for sleep quality," Dr. Janine Wirth, first author of the study, said.

Since the study is an observational one, the researchers could not establish a causative relationship between diet and sleep.

"Like other types of observational studies, cohort studies can suggest associations between an exposure and a health outcome but cannot prove causality. Residual confounding cannot be ruled out," Dr. Wirth added.