Difficulty Falling Asleep, Nocturnal Awakening, Sleep Dissatisfaction, and Irritability in the General Population.

Sleep disturbance is characterized by problems with sleep quantity and quality. However, the exact mechanisms and factors underlying sleep dissatisfaction in the general population remains unclear. This cross-sectional study collected sleep data and irritability level from individuals who visited hospitals for medical checkups or with unexplained physical symptoms using self-report questionnaires. This study included 328 individuals (157 males and 171 females). Bivariate correlation analyses revealed that irritability (ρ = 0.420; p < 0.0001), short sleep length (ρ = 0.405; p < 0.0001), difficulty falling asleep (ρ = 0.443; p < 0.0001), and nocturnal awakening (ρ = 0.528; p < 0.0001) were strongly correlated with sleep dissatisfaction. Multiple linear regression analyses among the overall individuals, following bivariate correlation analyses, indicated that stress at home (β = 0.245; p < 0.0001), irritability ( β= 0.172; p = 0.0021), difficulty falling asleep (β = 0.215; p < 0.0001), later bedtime (β = 0.140; p = 0.0331), and nocturnal awakening (β = 0.386; p < 0.0001) were independently correlated with sleep dissatisfaction, whilst short sleep length was not (β = 0.107; p = 0.1024). Further multivariable analyses revealed that difficulty falling asleep and nocturnal awakening were independently associated with each other. The obtained results were reproduced in the subgroup analyses among the 151 individuals taking medical checkups. In summary, major factors underlying sleep dissatisfaction in the general population included difficulty falling asleep and nocturnal awakening. Irritability was associated with difficulty falling asleep and sleep dissatisfaction. Carefully evaluating each of these sleep-related subscales and irritability may be beneficial in managing individuals with sleep problems.