Study shows cannabis is not associated with better sleep quality

Researchers followed 1,266 Black and white adults from the CARDIA cohort for nearly 35 years, repeatedly tracking lifetime and recent cannabis use, then measured sleep in middle age with a week of wrist-worn monitoring and self-report surveys. The analysis compared objective sleep metrics to participants’ perceptions and adjusted for many confounders, including age, sex, race, cigarette and alcohol use, physical activity, depression, chronic conditions and other substances. Results were published in JAMA Network Open and supported by the National Heart, Lung, and Blood Institute and collaborating institutions.

Greater cumulative and recent cannabis exposure was linked to poorer objectively measured sleep: lower sleep efficiency (percent of night asleep), more fragmented sleep, longer wake-after-sleep-onset, and a higher likelihood of sleeping more than eight hours. Despite these objective disruptions, cannabis users generally did not report worse sleep quality. The research did not distinguish consumption modes and cannot establish causation, but it counters the common belief that cannabis improves sleep. Authors emphasize known sleep-promoting practices - regular bedtimes, a cool dark environment, reduced screen time before bed, and calming routines - and recommend clinical evaluation if sleep problems persist.