Associations of Protein, Fat, and Carbohydrate Intakes With Insomnia Symptoms Among Middle-aged Japanese Workers

BACKGROUND Diet is a modifiable factor that may affect sleep, but the associations of macronutrient intakes with insomnia are inconsistent. We investigated the associations of protein, fat, and carbohydrate intakes with insomnia symptoms. METHODS In this cross-sectional analysis of 4435 non-shift workers, macronutrient intakes were assessed by the brief-type self-administered diet history questionnaire, which requires the recall of usual intakes of 58 foods during the preceding month. Presence of insomnia symptoms, including difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), and poor quality of sleep (PQS) were self-reported. Logistic regression analysis was used to estimate odds ratios (ORs) and 95% CIs adjusted for demographic, psychological, and behavioral factors, as well as medical histories. RESULTS Low protein intake (<16% vs ≥16% of total energy) was associated with DIS (OR 1.24, 95% CI 0.99-1.56) and PQS (OR 1.24, 95% CI 1.04-1.48), while high protein intake (≥19% vs <19% of total energy) was associated with DMS (OR 1.40, 95% CI 1.12-1.76). Low carbohydrate intake (<50% vs ≥50% of total energy) was associated with DMS (OR 1.19, 95% CI 0.97-1.45). CONCLUSIONS Protein and carbohydrate intakes in the daily diet were associated with insomnia symptoms. The causality of these associations remains to be explained.