Role of Sleep Reactivity in Shift Work Disorder

Sleep Reactivity as a Novel Mechanism in Shift Work Disorder

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.

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.

Inclusion Criteria:

• Participants must be working a fixed nightshift schedule, operationalized as: a) working at least three night shifts a week, b) shifts must begin between 18:00 and 02:00, and last between 8 to 12 hours, and c) must also plan to maintain the nightshift schedule for the duration of the study
• Participants must have Shift Work Disorder, which will be diagnosed based on ICSD-3 criteria
• Participants must show circadian misalignment, operationalized as a baseline melatonin onset between 18:00 and 01:00.
• Participants must be at least 18 years old

Exclusion Criteria:

• Insomnia disorder or excessive sleepiness predating the onset of shift work
• Termination of nightshift schedule
• Presence of other sleep disorders (e.g. obstructive sleep apnea, narcolepsy) determined by standard clinical polysomnography
• Diagnosis of bipolar disorder
• History of neurological disorders determined by self-report and medical history
• Pregnancy
• Alcohol use disorder
• Illicit drug use via self-report and urine drug screen if reasonable suspicion to test