The Effects of Cognitive Behavioral Therapy for Insomnia on Physical Activity Before and After Time in Bed Among Shift Workers

<b>Background:</b> Sleep and physical activity (PA) are bidirectionally related, with PA having a positive effect on sleep, and sleep quality influencing PA the following day. However, little is known about the effects of clinical interventions for sleep disorders on PA. Therefore, the aim of this secondary analysis is to evaluate the impact of cognitive behavioral therapy for insomnia (CBT-I), the first-line treatment for insomnia, on PA. <b>Methods:</b> Thirty-eight nurses with shift work disorder and insomnia were randomly assigned to either CBT-I or a waitlist control group. PA was measured for one week before (T0) and after the intervention/waiting period (T1) using actigraphy and sleep diary items. The impact of CBT-I on the PA parameters was analyzed using linear mixed models. In addition, correlations of pre-to-post-treatment changes in PA and pre-to-post-treatment changes in the clinical outcomes (insomnia severity, sleep efficiency, depression) were explored in the CBT-I group. <b>Results:</b> CBT-I increased actigraphy-derived PA during the two hours (β = 26.17, SE = 9.41, <i>p</i> = 0.009) and one hour (β = 13.24, SE = 4.57, <i>p</i> = 0.006) after time in bed, and resulted in a higher percentage of self-reported days with PA (β = 19.11, SE = 9.36, <i>p</i> = 0.049) compared to the waitlist control group. No significant correlations were found between the changes in PA and clinical outcomes, except for a moderate positive correlation between changes in self-reported sleep efficiency and changes in PA one hour before time in bed (r = 0.56, <i>p</i> = 0.013). <b>Conclusions:</b> This is the first study to investigate the impact of CBT-I on PA, providing preliminary evidence of the potential positive effects. Further studies with larger sample sizes and randomized controlled designs with continuous PA monitoring are needed to confirm these preliminary results.