Beneficial Effects of Appropriate Sleep Duration on Depressive Symptoms and Perceived Stress Severity in a Healthy Population in Korea

Background: Recently, several institutions, including the American Academy of Sleep Medicine, the Sleep Research Society, and the National Sleep Foundation, have made consensus recommendations concerning appropriate sleep duration for adults. Although numerous studies conducted in Western populations have provided evidence of the harmful effects of short or long sleep duration on mental health, it is still unclear whether these consensus recommendations are appropriate in Korean culture. Methods: Data from 1,892 subjects with no history of medical or psychiatric diagnoses were selected from the Korea National Health and Nutrition Examination Survey of 2014. Subjects were divided into seven groups based on their sleep duration (<= 4, 5, 6, 7, 8, 9, and >= 10 hours). Depressive symptoms were measured using the Patient Health Questionnaire-9 and perceived stress severity was evaluated using a Likert-type scale. Group differences in depressive symptoms and severity of stress were analyzed using an analysis of covariance. Results: Depressive symptoms in subjects with sleep duration of <= 4 hours (5.7 +/- 5.9) or 5 hours (3.4 +/- 3.9) were higher than in subjects with a sleep duration of 7 (2.2 +/- 2.9) or 8 hours (2.2 +/- 2.9) (corrected P<0.05). Furthermore, subjects with a short sleep duration (5 hours or below) had greater perceived stress severity than subjects with a sleep duration of 7 or 8 hours (corrected P<0.05). Conclusion: Our results suggest that maintaining an appropriate sleep duration as found in the recent consensus recommendation is important for mental health, even in healthy subjects without any medical or psychiatric illnesses, in Korea.