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Introduction Around 33% of shift workers suffer from shift work disorder (SWD). SWD includes insomnia and sleepiness related to the atypical work schedule. Most SWD treatments rely on light therapy or pharmacology. Few studies explored CBT-I efficacy for insomnia in shift work and reported promising results. The study aims to evaluate the efficacity of a behavioral therapy for insomnia adapted for SWD (BT-SWD). Methods Forty-three night shift workers meeting SWD criteria were recruited (mean age = 34 years old; 77% women) and randomized to either BT-SWD or waiting list control group. Eight participants dropped-out while waiting. Before and after treatment, participants completed questionnaires (ESS, ISI, STAI and BDI-II) and sleep diaries throughout the experimentation. BT-SWD involves sleep restriction therapy and stimulus control for insomnia as well as fixed sleep periods in the dark for shift workers. BT-SWD has been applied to night sleep, day sleep, and naps in this order. It consists of 6 sessions of 50 minutes delivered on 8 weeks. A mixed MANOVA was conducted on questionnaires scores with group (treatment or waitlist) as the between-subject factor and time as the within subject factor. Results A multivariate interaction effect was significant, F(6,21) = 8.24, p<.001. A univariate interaction effect was observed for the BDI-II (p=.042), the trait scale of the STAI (p=.021) and the ISI, both for night sleep (p=.027) and day sleep (p<.001), indicating that the scores of participants in the treatement group lowered significantly more than those of participants on the waiting group. The treatment group had a significantly less severe insomnia, both for day sleep during night work (p<.001), and night sleep during days off (p<.001). There was no significant difference between the control and the treatment group on sleepiness levels. Conclusion BT-SWD is effective at reducing insomnia severity as well as levels of trait anxiety and depression. Results are more equivocal for sleepiness. The waiting list control group design used has led to an important attrition in the context of shift work. Further analyses are needed to determine the BT-SWD efficacy on sleep variables. Support (if any) The study was supported by a CIHR grant (#110254) awarded to the first author

To better understand Shift Work Disorder (SWD), this study investigates insomnia, sleepiness, and psychosocial features of night workers. The study compares night workers with or without SWD to day workers with or without insomnia. Seventy-nine night workers and 40 day workers underwent diagnostic interviews for sleep disorders and for psychopathologies. They completed questionnaires and a sleep diary for 14 days. The design was observatory upon two factors: Work schedule (night, day work) and sleep (good sleep, SWD/insomnia). Two-way ANCOVAs were conducted on psychosocial variables, and effect size were calculated. The clinical approach chosen led to distinct groups of workers. Night workers slept several periods (main sleep period after work, naps, nights on days off). High total wake time and low total sleep time characterized sleep in SWD. Most night workers with SWD still complained of sleepiness after main sleep. Cognitive activation distinguished groups of night workers. All other differences in psychosocial variables between night workers groups were similar to, but smaller than, the ones between day workers. The evaluation of SWD should consider all sleep periods of night workers with particular attention to self-reported total wake time, state sleepiness, and level of cognitive activation.