Total dairy consumption is associated with healthy sleep patterns in U.S. adults

Evidence of dairy's association with sleep is limited. Therefore, we evaluated the association between dairy product consumption and self-reported and objective sleep outcomes in U.S. adults.

Participants included 23,480 men and women (mean age 46.7 ± 17.3 years) from the 2005-2020 National Health and Nutrition Examination Survey. Dairy intake (total and sub-types) was estimated from two 24-h dietary recalls. We categorized average daily dairy intake as low, moderate, and high based on sex-specific tertiles. Sleep duration (< 7, 7-9 (ref.), ≥ 9 h/day) and trouble sleeping (yes/no) were obtained from questionnaires. Objective sleep measures were derived from accelerometer data in a subsample (n = 4,972). Survey-weighted multivariate logistic and linear regression were used to evaluate dairy intake in relation to self-reported and objective sleep outcomes, respectively.

Mean (SD) total dairy intake was 1.76 (1.34) cup-eq/day. High total dairy intake was associated with 16% and 23% lower odds of short and long sleep duration, respectively (all P-trend ≤ 0.01), and lower odds of trouble sleeping (OR_{high vs. low}=0.86; 95% CI 0.75-1.00; P-trend < 0.05). Similar associations between milk and sleep duration, and high-fat dairy and trouble sleeping were observed (all P-trend < 0.03). Moreover, high vs. low total dairy intake was associated with a higher sleep regularity index, and fermented dairy intake was associated with less variable sleep midpoint, and lower odds of poor sleep (all P-trend < 0.03).

Dairy consumption is associated with improved odds of adequate sleep, no trouble sleeping, and less variable sleep in U.S. adults. However, additional studies are warranted to assess causality. Current Knowledge/Study Rationale: Emerging research suggests that diet influences sleep health; however, evidence on the specific role of dairy products remains limited. We examined the association between dairy product consumption (total and subtypes) and both self-reported and objective sleep metrics in a nationally representative sample of U.S. adults. Study Impact: Dairy intake, especially of fermented dairy products, is associated with better sleep patterns, via improved odds of having adequate sleep, no trouble sleeping, and less sleep variability. Longitudinal studies and clinical interventions are needed to investigate causal associations and to clarify underlying mechanisms.