Cannabis use as a moderator of cognitive behavioral therapy for insomnia

Study objectives: Cannabis use is common among young adults and has been proposed as a potential treatment for insomnia. However, controlled studies examining the impact of cannabis use on insomnia symptoms are rare. This secondary analysis of published trial data tested cannabis use during cognitive behavioral treatment for insomnia (CBT-I) as a moderator of treatment efficacy.

Methods: Young adults (ages 18-30 years) who reported past-month binge drinking (4/5+ drinks for women/men) and met DSM-5 and research diagnostic criteria for Insomnia Disorder were randomized to CBT-I (n=28) or sleep hygiene (SH; n=28). Interaction effects were tested using multilevel models. Outcomes included insomnia severity, actigraphy-assessed sleep efficiency, diary-assessed sleep quality, drinking quantity, and alcohol-related consequences.

Results: Twenty-six participants (46%; 12 SH and 14 CBT-I) reported using cannabis during the treatment phase of the study, on an average of 23% of treatment days (range=3-100%). Relative to those who did not use cannabis, participants who used cannabis during treatment reported heavier drinking and more frequent cigarette use. Approximately 1 in 4 cannabis users (27%) reported using cannabis to help with sleep; however, cannabis and non-cannabis users did not differ in use of alcohol as a sleep aid. Controlling for sex, race, drinking quantity, cigarette use, symptoms of depression, and symptoms of anxiety, use of cannabis during treatment did not moderate CBT-I effects on insomnia severity (b= -.002, p=.99) or other outcomes (all p >.20).

Conclusions: CBT-I is effective in reducing insomnia symptoms among young adult drinkers with insomnia, regardless of cannabis use.

Clinical trial registration: Registry: ClinicalTrials.gov; Identifier: NCT03627832.