Cognitive behavioral therapy for chronic insomnia in occupational health services: analyses of outcomes up to 24 months post-treatment.

Objective: Cognitive behavioral therapy for insomnia (CBT-I) is an effective treatment for persistent insomnia. The purpose of this study was to examine the effectiveness of and response patterns to CBT-I among daytime and shift workers with insomnia over a 24-month follow-up in occupational health services (OHS).

Methods: The participants were 59 media workers with chronic insomnia, of whom 69% were reached at 24-month follow-up. Sleep diaries and questionnaires over seven measurement points were used as outcomes. Trained OHS nurses led the CBT-I groups. The study design was a non-randomized group intervention.

Results: Self-perceived severity of insomnia, sleep-related dysfunctional cognitions, and psychiatric symptoms in particular showed improvements over a 24-month follow-up. Working hour arrangements did not affect the results. Based on the Insomnia Severity Index (ISI), 62% of the participants showed a moderate improvement after CBT-I, whereas the remaining participants showed only a minor improvement.

Conclusions: Our results indicate that CBT-I delivered by OHS leads to long-term improvements among both daytime and shift workers. Two groups were identified according to the degree of improvement of insomnia; one comprising two thirds of the participants with a moderate response and the other comprising one thirds of the participants with a modest response. The results need to be interpreted cautiously as insomnia was mild (ISI was on average under 15 points at all measurement points) and improvements were relatively small in the sample, and the study design was non-randomized.