To examine the prospective effects of psychosocial job characteristics evaluated with
the Demand-Control-Support (DCS) and Effort-Reward Imbalance (ERI) models on insomnia.
A prospective cohort study with a two-year observation was performed. The subjects
were 1022 middle-aged (>or= 39 years) Japanese workers. The following associations
were analyzed: high job strain, low social support, effort-reward imbalance, and overcommitment
to work at the baseline with self-reported persistence and future onset of insomnia.
Among those who were insomniacs at the baseline (N=292), low social support [adjusted
odds ratio (95% CI): 2.00 (1.18, 3.40)] and effort-reward imbalance [2.40 (1.13, 5.10)]
at the baseline had a significant relationship to insomnia at the follow-up. Among
those who were not insomniacs at the baseline (N=730), overcommitment to work [1.75
(1.16, 2.66)] and high job strain [1.72 (1.06, 2.79)] at the baseline were associated
with insomnia at follow-up.
Prospective effects of psychosocial job characteristics on insomnia differed between
its persistence and future onset. Proportionate reward for work effort and sufficient
support at work assist recovery from insomnia, while overcommitment to work and high
job strain cause future onset of insomnia.