Effect of cognitive behavioral therapy for insomnia in workers: A systematic review and meta-analysis of randomized controlled trials

Behavioural therapy for shift work disorder improves shift workers' sleep, sleepiness and mental health: A pilot randomised control trial

The present study evaluates the efficacy of behavioural therapy adapted for shift work disorder with a randomised control design in a healthcare population. Forty-three night shift workers (m. age: 34 years; 77% women) experiencing shift work disorder were randomised to either the behavioural therapy for shift work disorder (BT-SWD) or a waiting-list control group offered after the waiting period. Participants completed questionnaires on insomnia, sleepiness and mental health pre- and post-treatment, pre- and post-waiting, and at follow-up, and a sleep diary. As night shift workers alternate between sleeping during the day after their night shifts and transitioning to nighttime sleep on days off, insomnia severity and sleep variables were analysed for daytime and nighttime sleep. The BT-SWD involved sleep restriction therapy, stimulus control and fixed sleep periods in the dark. Statistical analyses were performed under intent-to-treat and per-protocol approaches. Repeated-measures two-way ANCOVA analysis, controlling for age, sex and pre-treatment daytime total sleep time, was performed with Bonferroni corrections, and between-group effect sizes computed. Fourteen participants dropped out after randomisation. Under the intent-to-treat analysis, BT-SWD participants had a significant greater decrease in daytime insomnia severity and an increase in daytime total sleep time at post-treatment than the control group, with large between-group effect sizes (-1.25 and 0.89). These corresponding results were also significant with large effect sizes under the per-protocol analysis. Sleepiness, anxiety and depression levels improved at post-treatment and maintained at follow-up when the BT-SWD treated controls were added to the BT-SWD group. The behavioural therapy for shift work disorder can be used to improve the sleep and mental health of healthcare night workers.

Psychometric properties of the Japanese version of the Insomnia Catastrophizing Scale and relationship of insomnia severity with catastrophic thoughts, safety behaviors, and dysfunctional beliefs

BACKGROUND

This study aimed to clarify the reliability and validity of the Japanese version of the Insomnia Catastrophizing Scale (ICS) and to examine the relationship between insomnia severity and insomnia-related cognitive factors.

METHODS

A total of 786 participants were recruited via an online survey and classified into the insomnia group (n = 342) and healthy group (n = 444). The insomnia group comprised individuals who self-reported meeting the diagnostic criteria for chronic insomnia disorder in the third edition of the International Classification of Sleep Disorders.

RESULTS

The ICS is used to independently assess nighttime (ICS-N) and daytime (ICS-D) catastrophic thoughts, and item response theory revealed that each ICS-N and ICS-D item can adequately assess catastrophic thoughts during the night and day, respectively. The internal consistency and test-retest reliability of the ICS-N and ICS-D were good. Further, the ICS-N and ICS-D had a significant positive correlation with insomnia severity, hyperarousal, sleep-related safety behaviors, dysfunctional beliefs about sleep, and anxiety symptoms. Multiple regression analyses with insomnia severity as the dependent variable in the insomnia group demonstrated that catastrophic thoughts were more strongly associated with insomnia severity than sleep-related safety behaviors and dysfunctional beliefs about sleep. The interaction between nighttime catastrophic thoughts and sleep-related safety behaviors increased insomnia severity.

CONCLUSIONS

The Japanese versions of ICS-N and ICS-D were found to be superior in measuring insomnia-related catastrophic thoughts and to have high reliability and validity. Furthermore, these findings more clearly demonstrate that the catastrophic thoughts may be an important associated factor of insomnia.

Network analysis to estimate central insomnia symptoms among daytime workers at-risk for insomnia

Although insomnia complaints are associated with mental health problems and reduced work productivity, the central insomnia symptoms in workers at-risk for insomnia remain unclear. This study aimed to identify the central insomnia symptoms among daytime workers at risk for insomnia. The participants were 881 Japanese daytime workers at-risk for insomnia with a mean age of 49.33 ± 9.92 years. At-risk for insomnia was defined as an Athens Insomnia Scale score of six or higher. The Athens Insomnia Scale was used as a screening for at-risk insomnia because it has higher sensitivity and specificity than other insomnia screening scales. The Insomnia Severity Index is recommended as a mechanism of insomnia and an outcome measure; therefore, a network analysis was conducted with the seven items of the Insomnia Severity Index. The important variables in the connections between insomnia symptoms were estimated from centrality indices, which were interpretable only for strength. The strength value results suggest that difficulty staying asleep and worry about sleep problems were the central insomnia symptoms. The connections were stronger for difficulty staying asleep and problem waking up too early, difficulty staying asleep and difficulty falling asleep, and interference with daytime functions and noticeable to others. Worry about sleep problems was strongly associated with variables other than nocturnal insomnia symptoms. Therefore, difficulty staying asleep and worry about sleep problems are important variables in daytime workers at-risk for insomnia and are key points for improvement or exacerbation of insomnia symptoms.