Short Sleep Duration and Insomnia Symptoms were Associated with Lower Happiness Levels in Chinese Adults in Hong Kong

Study objective: To examine the association of sleep duration and insomnia symptoms with happiness. Methods: A random sample of 1691 Chinese adult (mean age 54 ± 20.1, male 51%) were interviewed in a population-based telephone survey. Happiness was measured by the subjective happiness scale (SHS) and the one-item global happiness index (GHI). Information on sleep included mean past seven-day sleep duration (<6 h, ≥6 to <8 h and ≥8 h) and insomnia symptoms: Difficulty in initiating sleep (DIS), difficulty in maintaining sleep (DMS), and early morning awakening (EMA). Adjusted beta-coefficient (β) of SHS and adjusted odds ratio (aOR) of GHI in relation to sleep problems were calculated. Interaction effects by age (18-65 vs. ≥65) and by sex were assessed. Results: Compared to ≥8 h of sleep, having <6 h of sleep had lower SHS (adjusted β -0.32, 95% CI -0.46 to -0.17) and GHI (aOR 0.54, 95% CI 0.38 to 0.78). The associations were stronger in younger adults and in women (p < 0.05). DIS, DMS, and EMA were associated with lower SHS (adjusted β ranged from -0.20 to -0.06) and GHI (aOR ranged from 0.57 to 0.89). Dose-response association between the number of insomnia symptoms and lower SHS was observed (p < 0.001). These associations were generally stronger in older adults and among women. Conclusions: Lower levels of happiness were observed, particularly in younger adults and females with short sleep duration and older adults and females with insomnia symptoms. Prospective studies are needed to confirm the findings and understand the mechanisms between sleep and happiness.