[Introduction] Although mental health care is important, at present, effective preventative methods for mental disfunction are underdeveloped. Mental health problems can be caused by psychological factors such as job stressors and stressful life events. Recently, the association of lifestyle and sleep with mental health has gained attention; however, few studies have comprehensively investigated multiple lifestyle factors and sleep while controlling for job stressors in office workers. We performed a longitudinal study to clarify the effects of lifestyle and sleep factors on the mental health of office workers.
 [Materials and Methods] In 2017, 3,314 employees from 17 companies were invited to participate in the survey. Complete responses and informed consent were provided by 2,905 participants, and of those, 2,289 participants answered the survey again in 2018. The effects of the participants' lifestyle and sleep on their current psychosomatic stress reactions were analyzed by multiple linear regression and a cross-lagged model by structural equation modeling.
 [Results] When controlled for job stressors or social support, commuting time, irregular mealtimes, not eating vegetables daily, alcohol intake, not seeing morning sunlight in the bedroom, dinner within 1 hour before bedtime, using electronic devices before bed or in bed, nighttime caffeine intake, and sedentary behavior were associated with changes in psychosomatic stress reactions. The cross-lagged model demonstrated that the degree of estimation from a participant's previous lifestyle factors or sleep disturbance to current stress reactions were greater than that from previous stress reactions to current lifestyle factors or sleep disturbance.
 [Conclusion] Lifestyle problems and sleep disturbance led to psychosomatic stress responses independently from controlling factors such as job stressors. Therefore, improving lifestyle factors and sleep factors associated with stress reactions may be a primary prevention method for mental health dysfunction.
 Authors' abstract