The first aim of this study is to establish sleep reactivity as a predictor of insomnia in SWD independent from circadian misalignment. The second aim of this study is to establish sleep reactivity as a predictor of sleepiness in SWD independent from circadian misalignment. The third aim of this study is to probe sleep reactivity as a cause of insomnia in SWD. The fourth aim of this study is to probe sleep reactivity as a cause of sleepiness in SWD.~Participants with Shift Work Disorder (SWD, N=150) with high and low sleep reactivity will be enrolled. This study will use a two-step mechanistic randomized controlled trial design stratified by high and low sleep reactivity to examine the independent effect of sleep reactivity in SWD after experimental reduction of circadian misalignment. The first step will experimentally reduce circadian misalignment compared to a control. Those who achieve reduced circadian misalignment (melatonin onset at or later than 4am, i.e., compromised phase position) and remain symptomatic will continue to the second step where sleep reactivity will be probed with CBT compared to a sleep education control.
The purpose of this project is to test sleep reactivity as an independent cause of Shift Work Disorder (SWD). The primary hypothesis is that those with high sleep reactivity will show persistent SWD symptoms after experimental reduction of circadian misalignment, which will then be mitigated with CBT.