Greater adherence to healthful dietary patterns is associated with lower insomnia risk in the Women's Health Initiative Observational Study.

STUDY OBJECTIVES: Insomnia is highly prevalent among postmenopausal women and is associated with adverse health outcomes, highlighting the need to identify modifiable determinants of sleep. Diet and sleep are interrelated; however, few studies have evaluated longitudinal associations of complete dietary patterns with incident insomnia in postmenopausal women. This study evaluates prospective associations of established diet quality metrics with insomnia in the Women's Health Initiative Observational Study (WHI-OS). METHODS: The WHI-OS enrolled 93 676 postmenopausal women from across the United States. Alternate Mediterranean (aMed) diet and Dietary Approaches to Stop Hypertension (DASH) diet quality scores were quantified from a Food Frequency Questionnaire at baseline and dichotomized scores using a data-driven approach. Insomnia was assessed at baseline and Year 3 using the WHI Insomnia Rating Scale. Multivariable logistic regression models adjusted for sociodemographic, lifestyle, and health factors evaluated associations of baseline diet quality with incident insomnia and longitudinal insomnia status (stable/new onset insomnia vs. stable absence/remission of insomnia). RESULTS: Among women without insomnia at baseline (n = 50 644), good vs. poor diet quality at baseline was associated with lower risk for incident insomnia at 3-year follow-up (OR [95% CI], aMed: 0.925 [0.879-0.974], p=.003; DASH: 0.937 [0.891-0.985], p=.01]). In longitudinal analyses (n = 74 513), greater baseline adherence to aMed and DASH diets related to 6.3% (0.903-0.971) and 8.5% (0.883-0.948) lower odds, respectively, of having stable or new onset insomnia over 3 years (both p<.005). CONCLUSIONS: Better diet quality predicts lower insomnia risk in postmenopausal women. Clinical trials are needed to determine whether strategies to enhance diet quality improve insomnia symptoms. CLINICAL TRIAL INFORMATION: The Women's Health Initiative Observational Study is registered on Clinicaltrials.gov #NCT00000611: https://clinicaltrials.gov/study/NCT00000611.