Longitudinal trends in disaster-related insomnia among Fukushima nuclear plant workers: the Fukushima Nuclear Energy Workers' Support Project study.

STUDY OBJECTIVE

To determine longitudinal effects of experiences related to the Fukushima nuclear disaster on March 11, 2011, on insomnia risk among workers of nuclear power plants on identified disaster-related potential risk factors for the subtypes of insomnia.

METHODS

We included a total of 1403 workers who responded to a questionnaire on insomnia-related symptoms measured by the Athens Insomnia Scale from 2011 to 2014 and on disaster-related experiences in 2011. We examined the longitudinal relationships between disaster-related experiences and insomnia using mixed-effect logistic regression models. We also used path analysis to examine the potential effects of disaster-related experiences on the subtypes of insomnia (i.e. initial, sleep maintenance, and early morning awakening).

RESULTS

All disaster-related experiences were significantly associated with insomnia, except death of a family member or colleague. We found that most of these types of traumatic exposure were associated with the risk of insomnia in a time-independent way. However, the effect of experiencing life-threatening danger decreased with time. Based on the results of the path analysis, we found that life-threatening experiences, such as experiences of life-threatening danger or witnessing the explosion, may conjure up disturbing scenes that hamper sleep initiation. On the other hand, early morning awakening may be related to life uncertainty. We found that social discrimination/slurs was associated with all three types of insomnia and was also influenced by other experiences, such as life-threatening danger, property loss, and colleague death.

CONCLUSION

Our findings emphasize the importance of comprehensive psychosocial support for workers with disaster-related experiences.