Psychiatry · Medical Literature
Efficacy of an anonymous, preventive, personalized online counselling to improve shift workers' sleep quality: a randomized controlled trial.
Abstract
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.
Clinical relevance
Shift workers represent a vulnerable occupational population with disproportionately elevated rates of insomnia and sleep disorders, yet evidence-based, scalable preventive interventions tailored to their unique circadian challenges remain scarce. This RCT addresses that gap by evaluating an anonymous, digitally delivered CBT-I–based counselling program specifically adapted for shift workers across multiple industries, a practically relevant model given the barriers shift workers face in accessing conventional in-person therapy. Clinicians managing occupational health, sleep medicine, or psychiatric comorbidities in this population need to understand both the promise and the current limitations of digital CBT-I adaptations for this group.
Key findings
1. In the intention-to-treat sample (n = 66), significant within-group improvements were observed for the primary outcome, sleep efficiency, in both the intervention and waiting-list control groups, but between-group superiority of the counselling intervention was not demonstrated. 2. Secondary outcomes including insomnia symptom severity and depressive symptoms improved significantly within both groups over the four-week period, again without statistically significant between-group differences favoring the intervention. 3. Daytime sleepiness did not improve significantly in either group, suggesting that a four-week, four-session digital intervention may be insufficient to address hypersomnolence in shift workers. 4. The intervention consisted of four personalized asynchronous counselling messages paired with four weekly sleep diary completions, while the control group completed sleep diaries only, indicating a possible therapeutic effect of self-monitoring alone (reactive or Hawthorne-type effect). 5. The study was underpowered relative to its superiority design, with a final per-arm sample limiting the ability to detect clinically meaningful between-group effect sizes; the authors explicitly acknowledge sample size and time frame as key limitations. 6. The anonymous, online delivery model was feasible across multiple German industries, supporting the scalability and accessibility of the platform, though efficacy over an active control could not be confirmed in this trial.
Practice implications
Clinicians should not yet adopt this specific four-session anonymous online CBT-I counselling model as a stand-alone evidence-based intervention for shift worker insomnia, as superiority over self-monitoring alone was not demonstrated in this adequately registered but underpowered RCT. However, the finding that structured sleep diary completion itself was associated with meaningful within-group improvements in sleep efficiency and insomnia symptoms suggests that prescribing self-monitoring tools (digital or paper sleep diaries) may be a low-cost, low-barrier first step for shift workers with mild-to-moderate sleep complaints. Future research should prioritize adequately powered trials with longer follow-up, active comparator arms, and dose-optimization of digital CBT-I modules specifically designed around rotating and night shift schedules before broad clinical implementation.