Relationship between Poor Sleep and Future Development of Depressive Symptoms in a 2-year Cohort Study of Male Japanese Workers

ABSTRACT

We examined the relationship between poor sleep and the future incidence of depressive symptoms through a 2-year cohort study of male Japanese workers at a synthetic fiber manufacturing plant. A questionnaire survey addressing job stress, sleep conditions, and depressive symptoms was conducted in 2007 and 2009 using the Athens Insomnia Scale (AIS-5) and the Job Stress Questionnaire. Poor sleep was assessed using the AIS, a tool devised by the World Health Or-ganization, based on criteria of the International Classification of Disease 10th Revision (ICD-10). Of the 158 respon-dents, 108 without depressive symptoms at baseline were analyzed. The incidence of new depressive symptoms was 10.2% over the 2 years. None of the subjects with AIS-5 scores of 0 in 2007 (baseline) suffered depressive symptoms in 2009, while 15.7% of the subjects with AIS-5 scores of 1 or more did so. Among those with AIS-5 scores of 3 or more in 2007, 20.0% experienced depressive symptoms in 2009. AIS scores at baseline were closely associated with the incidence of new depressive symptoms over the 2 years. Poor sleep can be a risk factor for developing depression or, at least, an im-portant marker for the subsequent development of depression among male Japanese workers.

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