The purpose of this study is to test the hypothesis that ingestion of the wake-inhibiting drug suvorexant 30 minutes prior to daytime sleep initiation in individuals working overnight shifts will significantly improve both objective (total sleep time, sleep efficiency, wake after sleep onset) and subjective (sleep quality) measures of daytime sleep.

Inclusion Criteria:

• Aged 20-60 (older individuals excluded due to altered sleep-related circadian signaling)

• Males and females

• Shift worker

  • Minimum of three months of prior shift work
  • Will work minimum of four nights per week or 32 hours of night shift per week during study
  • "Night work" defined as having at least six hours of work occurring between 8 PM and 8 AM and no longer than 12 hours on shift

• Presence of DSM-5 defined Circadian Rhythm Sleep-Wake Disorder: Shift Work Type

  • Insomnia (SE < 88%) during attempted daytime sleep or excessive sleepiness during nocturnal wake

Exclusion Criteria:

• Currently or planning to become pregnant
• Currently breastfeeding
• Inadequate opportunity (<7 hours) for daytime sleep after shift work
• Use of sleep aids during the study period. Includes as needed or continuous use of prescription, non-prescription, and naturopathic pharmacotherapies
• Diagnosis or detection (during study) of sleep disordered breathing (AHI>10) on home sleep testing; referral to clinical sleep program will be offered
• Diagnosis of narcolepsy
• Restless Legs Syndrome
• >600 mg caffeine intake per night shift or use of prescription stimulant medication during night shift
• Rotational or irregular work shifts during study
• Use of digoxin for six months prior to or during study
• Use of strong (e.g., etoconazole, itraconazole, posaconazole, clarithromycin, nefazodone, ritonavir, saquinavir, nelfinavir, indinavir, boceprevir, telaprevir, telithromycin, conivaptan) or moderate (e.g., amprenavir, aprepitant, atazanavir, ciprofloxacin, diltiazem, erythromycin, fluconazole, fosamprenavir, grapefruit juice, imatinib, verapamil) CYP3A inhibitors or CYP3A inducers (e.g., rifampin, carbamazepine, phenytoin) for six months prior to or during study
• Severe hepatic impairment
• Unstable or severe medical or psychiatric condition

All relevant data will be provided in the publication

5 weeks

Weekly and ad libitum telephone assessment with project coordinator