Does Daily Cannabis Quiet Your Sleep or Sabotage It?

You take something to fall asleep. You wake up feeling just... fine. But what if the clock and your body don’t tell the same story?

Researchers following participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study report a surprising mismatch between how people think they sleep and what wearable monitors record. Over nearly 35 years, data from 1,266 adults tracked patterns of cannabis use from young adulthood into middle age and then compared those histories with a week of wrist-worn sleep monitoring and self-reported sleep surveys in midlife.

Long-term exposure to cannabis was linked with a picture of sleep that looks good on the surface but frays when examined closely: more time awake after falling asleep, lower sleep efficiency, and a more fragmented night. Recent users also tended to log longer nights — often more than eight hours — yet their sleep was punctuated by interruptions. The striking part? Participants rarely said their sleep felt worse.

Long-term cannabis use was tied to more fragmented, inefficient sleep — even when people didn’t perceive any decline in quality.

“This challenges the common belief that cannabis helps people sleep better,” said Dr. Thanh-Huyen T. Vu of Northwestern Medicine, a lead author on the analysis published October 9 in JAMA Network Open. The pattern held up after accounting for age, sex, race, cigarettes, alcohol, physical activity, depression, chronic conditions and other substance use. That strengthens the association, though it does not prove cause and effect.

Think of it like a scratched record. The total playtime may look normal, but the music stutters. Wearable devices picked up the stutters; subjective ratings did not. Why the disconnect? People may adapt to subtle night-time awakenings or simply accept a groggy morning as normal, masking the underlying disturbance.

The CARDIA data do not break down how cannabis was consumed. Smoking, vaping, edibles — the study lumped these together, and patterns likely shifted across decades of follow-up. That nuance matters. Different delivery methods and changing potencies could mean different effects on sleep, and the authors flag this as a priority for future work.

If you’re trying to sleep better, the usual sleep-hygiene playbook still applies. Keep a steady bedtime. Make the room cool, dark and quiet. Put the phone away before bed. Build a calming ritual — reading, breathing, or a warm shower can help signal the body it’s time to wind down. And if sleep problems persist, or if you snore loudly, see a clinician to rule out an underlying disorder.

Cannabis is becoming more available and socially accepted. That makes it all the more important to understand its long-term effects on behaviors we barely notice until they add up.