2019 Volume 6 Issue 1 Pages 9-17
Objective: The purpose of this study was to perform a detailed statistical analysis on coffee’s effect on sleep in Japan from an epidemiological perspective.
Methods: Subjects were 9,839 men (mean age, 50.7 ± 9.2 years) and 7,148 women (mean age, 49.4 ± 8.9 years) who received a health check-up. Coffee intake, total sleep duration, and sleep satisfaction were investigated and evaluated using univariate and multivariate analyses.
Results: Our results are for: Coffee intake [<1 cup/day: n=5,430 (32.0%), 1 cup/day: n=2,540 (14.9%), 2 cups/day: n=3,647 (21.5%), and≥3 cups/day: n=5,370 (31.6%)], total sleep duration [average 6.1± 0.95 h/day; breakdown, <5 h/day: n=511 (3.0%), 5–7 h/day: n=10,842 (63.8%), 7–9 h/day: n=5,555 (32.7%), and ≥9 h/day: n=79 (0.5%)], sleep satisfaction [satisfaction: n=10,030 (59.0%), and dissatisfaction: n=6,957 (41.0%)]. Total sleep duration and sleep satisfaction increased with age, and were both poorer for women than men. Subjects satisfied with their sleep had a significantly longer sleep duration than those who did not (6.5 ± 0.85 h vs. 5.6 ± 0.82 h). Multivariate analyses showed that male gender, older age, smoking, drinking, and preferable dietary/fitness habits had a significantly positive association with both total sleep duration and sleep satisfaction.
Conclusions: Coffee had a weak but significant association with total sleep duration in subjects who drank ≥2 cups/day. On the other hand, no association was observed between coffee intake and sleep satisfaction.
