Efficacy study comparing a CBT-I developed for shift workers (CBT-I-S) to standard CBT-I (cognitive behavioural therapy for insomnia) on sleep onset latency, total sleep time, subjective sleep quality, and daytime sleepiness: study protocol for a parallel group randomised controlled trial with online therapy groups of seven sessions each.

Background: Shift workers are at an increased risk of developing sleep disorders. The standard therapy recommended for sleep disorders is cognitive behavioural therapy for insomnia (CBT-I). Many of its interventions are based on a regular sleep and wake rhythm, which is difficult to apply for shift workers. We have therefore developed a new therapy manual specifically for shift workers (CBT-I-S), which should be more applicable to their needs. In particular, all interventions that require regularity have been removed, and instead, interventions that address factors that proved to be relevant to sleep in our preliminary study have been integrated. We now want to test this manual for its effectiveness.

Methods: A randomised controlled trial with N = 142 will be conducted to compare two conditions: the newly developed therapy manual will be carried out in the experimental group, while cognitive behavioural therapy for insomnia will be employed in the standard group. Both treatments will be conducted online via MS Teams in a group setting with seven sessions each. Data will be collected at three measurement points (pre, post, 6-month follow-up) and analysed using linear mixed models. The study will investigate whether the two treatments have led to significant improvements in total sleep time, sleep onset latency, subjective sleep quality and daytime sleepiness in shift workers. It will also examine whether the new therapy manual is superior to standard therapy in shift workers and whether these effects are stable.

Discussion: We assume that interventions designed to address depressive mood, anxiety, worry, rumination, dysfunctional thought patterns and attitudes towards sleep will also improve sleep. If this is indeed the case, these interventions could replace previous ones that require regularity. This could significantly improve the treatment of insomnia in shift workers.

Trial Registration: German Clinical Trials Registry DRKS DRKS00032086 . Registered on August 16, 2023.