Relationship between insomnia with alcohol drinking before sleep (Ne-Zake) or in the morning (Mukae-Zake) among Japanese farmers

Background Ne-Zake is the drinking of alcohol before sleeping for helping to fall asleep and sleep well, and Mukae-Zake is the drinking of alcohol in the morning for “calming down” or “curing hangovers”. Objective We sought to examine the relationship of insomnia with Ne-Zake and Mukae-Zake among healthy middle-aged Japanese farmers. Methods In a cross-sectional study of 746 participants (mean age, 59.5 years; women, 25.9%), Ne-Zake and Mukae-Zake were defined based on a self-administered questionnaire. Insomnia was defined as the Athens Insomnia Scale Japanese version ≥6 or usage of sleeping pills in the previous year. Logistic regression was used to calculate odds ratio (OR) of insomnia related to Ne-Zake and Mukae-Zake adjusting for sex, age, presence of sleep-related disorders, frequency of alcohol consumption, and quantity of alcohol consumed per one occasion. Results We observed insomnia, Ne-Zake, and Mukae-Zake in 174 (23.3%), 140 (18.8%), and 37 (5.0%) participants, respectively. After adjustment for demographic and confounding factors, participants with Ne-Zake had a significantly higher prevalence of insomnia (OR 2.00 [95% confidence interval, 1.27–3.16]), compared to those without Ne-Zake. Mukae-Zake was also independently associated with a higher prevalence of insomnia among men (OR 3.26 [1.55–6.87]). Participants with both Ne-Zake and Mukae-Zake had a highly significant association with insomnia (OR 4.77 [2.01–11.3]) than those with neither Ne-Zake nor Mukae-Zake. Additionally, for insomnia, the association of Mukae-Zake was more pronounced than that of Ne-Zake (OR 4.09, 95% CI 1.14–14.7, p = 0.031; and OR 1.81, 95% CI 1.08–3.06, p = 0.026, respectively). Conclusion Ne-Zake and Mukae-Zake were associated with insomnia independent of the quantity and frequency of alcohol consumption among Japanese farmers. This finding can be used for stratifying individuals with insomnia not only to improve sleep hygiene but also to prevent alcohol dependence by informing the general population that alcohol has a negative effect on sleep, contrary to popular beliefs.