Efficacy of an anonymous, preventive, personalized online counselling to improve shift workers' sleep quality: a randomized controlled trial.

Shift work is associated with an increased risk of sleep disorders, yet tailored prevention and treatment programs remain rare and understudied. Cognitive behavioral therapy for insomnia is the first-line treatment for insomnia in the general population. We thus developed an anonymous online counselling service based on cognitive behavioral principles, adapted it to shift workers' needs, and evaluated it in a sample of German shift workers from various industries. This prospective, randomized, controlled superiority trial compares two parallel groups: an intervention group that received four personalized counselling messages and completed four weekly sleep diaries, and a waiting-list control-group that completed sleep diaries only during the four-week waiting period. In the Intention to Treat sample (n = 66), significant improvements were observed in both groups for the primary outcome, sleep efficiency, and for the secondary outcomes, symptoms of insomnia and depression. Daytime sleepiness did not improve in either group. However, improvements were not significantly greater in the treatment than in the control group. We can thus not demonstrate superiority of the counselling intervention over the control condition, where repeated sleep diary completion and study participation may themselves have had therapeutic effects. Limitations regarding time frame and sample size, as well as implications for research and practice are discussed.Trial registration: The study was registered with the German Clinical Trials Register DRKS under the trial ID DRKS00017777 ( https://drks.de/search/en/trial/DRKS00017777 ). Date of registration: 14.01.2020. This study was registered during the early stages of data collection. Of the 27 participants in the final sample, the first four had initiated data collection at the date of registration. No complete data sets were available at that time.