University of Adelaide researchers report that men who consume diets high in fat are more likely to experience daytime sleepiness, report poor sleep at night, and have a higher risk of obstructive sleep apnoea (OSA).
The findings come from analyses of the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) cohort, a community-based study led by the University of Adelaide’s Population Research and Outcome Studies unit in the School of Medicine and the Freemasons Foundation Centre for Men’s Health. The team examined dietary patterns and sleep outcomes to better understand links between macronutrient intake and both subjective and objective measures of sleep health.
Researchers drew on data from over 1,800 Australian men aged 35–80 years who provided information about their diet over a 12-month period. A subset of participants underwent overnight in-home polysomnography to assess sleep-disordered breathing objectively. The study’s detailed results were published in the peer-reviewed journal Nutrients.
“After adjusting for demographic factors, lifestyle, and chronic conditions, men consuming the highest proportion of energy from fat were significantly more likely to report excessive daytime sleepiness,” said study author Yingting Cao, a University of Adelaide PhD candidate based at the South Australian Health and Medical Research Institute (SAHMRI). “High fat intake was also strongly associated with higher apnoea-hypopnoea index (AHI), indicating more severe sleep apnoea.”
Across the sample with available dietary and sleep information, 41% reported experiencing daytime sleepiness and 47% reported poor sleep quality at night. Objective measures showed a high prevalence of sleep-disordered breathing: roughly 54% had mild-to-moderate OSA, and about 25% met criteria for moderate-to-severe OSA among those assessed by sleep study who did not have a prior diagnosis.
The research highlights a potentially self-reinforcing cycle between diet and sleep. “Poor sleep and daytime sleepiness reduce energy and can increase cravings for high-fat, high-carbohydrate foods,” Ms Cao explained. “Those food choices can, in turn, worsen sleep outcomes, creating a vicious cycle that may impair alertness, concentration and overall health.”
Study authors note that body mass index (BMI) partially mediated the association between fat intake and obstructive sleep apnoea, accounting for about 30% of that relationship, but BMI did not explain the link between high fat intake and daytime sleepiness. No consistent associations were found between intake of other macronutrients and sleep outcomes in this analysis.
“The simple, practical message is commonsense: improving diet quality and prioritizing good sleep can both support better daytime alertness and reduce sleep-disordered breathing risk,” Ms Cao said. She also emphasized that many dietary intervention studies focus on weight loss without adequately measuring sleep outcomes. These results suggest sleep should be assessed more routinely in trials that alter macronutrient composition.
Funding: The study was supported by the National Health and Medical Research Council (NHMRC) and the ResMed Foundation.
Study team and source: Lead author Yingting Cao and colleagues at the University of Adelaide reported results from the MAILES cohort, with additional contributors including Gary Wittert, Anne W. Taylor, Robert Adams and Zumin Shi.
Research summary (abstract): A cross-sectional analysis of MAILES participants investigated associations between macronutrient intake and sleep outcomes. Dietary intake was assessed by a validated food frequency questionnaire. Self-reported measures covered poor sleep quality and daytime sleepiness, while overnight in-home polysomnography assessed obstructive sleep apnoea in participants without a prior diagnosis. After adjustment for demographic, lifestyle and chronic disease factors, the highest quartile of fat intake was associated with greater risk of excessive daytime sleepiness (relative risk ratio 1.78) and with higher apnoea-hypopnoea index (AHI ≥ 20; relative risk ratio 2.98). BMI mediated part of the association between fat intake and AHI, but not between fat intake and daytime sleepiness. No clear associations were observed for other macronutrients. The authors concluded that high dietary fat is associated with daytime sleepiness and increased AHI, and they recommended that sleep outcomes be considered in dietary intervention studies targeting macronutrient composition.
This research underscores the public health importance of considering both diet and sleep together when addressing fatigue, cognitive performance, workplace safety, and strategies for healthy weight management.