The purpose of the present study was to evaluate the relationship between sleep disturbances and depression in the Japanese elderly.
Methods: These investigations in the Japanese elderly were carried out with the Geriatric Depression Scale, the Pittsburgh Sleep Quality Index, and questions on restless legs syndrome and nocturnal eating disorder. A total of 2023 people (male: 1008; female: 1015; average age: 74.2 +/- 6.3 years) were analyzed by chi2 test and simple and multiple logistic regression. The prevalence of sleep disturbance was 37.3% and that of depression was 31.3%. Female gender and/or older (> or =75 years) age were significantly associated with depression. Characteristics in depressive elderly were poor sleep efficiency, sleep disturbances due to difficulty of initiating sleep (DIS), breathing discomfort, coldness and pain, poor subjective sleep quality and lack of enthusiasm for activities. Sleep disturbances due to using the bathroom, breathing discomfort and coldness and long sleep latency were associated with depression in younger (65-74 years) men. Sleep disturbance due to DIS was associated with depression in older (> or =75 years) men. Sleep disturbance due to pain was associated with depression in younger and older women. Poor sleep efficiency was associated with depression in older women. Poor subjective sleep quality was associated with depression in younger and older men and younger women. Lack of enthusiasm was associated with depression in younger and older men and older women. Restless legs syndrome was statistically significantly associated with depression in younger men. It is concluded that sleep disturbance and depression among the Japanese elderly are closely related symptoms. The features of sleep disturbance with depression differed with sex and age.