Marijuana Used as a Sleep Aid Is Actually Making Sleep Worse, New Study Finds

Many people turn to marijuana for sleep problems, but a new study says cannabis users' sleep quality is objectively worse — even though they do not perceive it that way. The Northwestern Medicine study included 1,266 participants.

Researchers monitored the participants for almost 35 years, from young adulthood into middle age, tracking their cannabis use over time. In middle age, participants wore a sleep monitor on their wrist for a week and also filled out surveys about their sleep quality.

Comparing the two sets of data, researchers found that both lifetime and recent cannabis users had worse sleep quality on objective measures, although they did not report their sleep to be worse.

Greater lifetime exposure to marijuana was linked to sleeping for a lower percentage of the night and experiencing more sleep disruption. Recent cannabis users were more likely to have more sleep fragmentation and lower sleep efficiency compared to people who never used the substance. At the same time, recent users had a much higher chance of sleeping longer than eight hours per night.

"Our data do not support the belief that cannabis is helpful as a sleep aid," said senior study author Mercedes R. Carnethon. She added that as cannabis becomes increasingly available and accepted, it is important to better understand its long-term associations with health behaviors such as sleep.

Alfred Joshua, a board-certified emergency medicine physician based in California who was not involved in the study, said what makes it particularly interesting is that participants who used cannabis demonstrated objectively poorer sleep, yet their own assessments did not reflect those differences. In other words, someone may believe marijuana is helping them sleep, while objective measurements suggest otherwise.

Researchers considered multiple outside factors, including age, race, sex, smoking frequency, alcohol consumption and physical activity. Even with these factors taken into account, the study found a consistent correlation between cannabis use and poorer objectively measured sleep. The mode of consumption, such as smoking versus edibles, was not considered.

Joshua said the researchers found that greater cumulative cannabis exposure was associated with reduced sleep efficiency, increased sleep fragmentation and more time spent awake after initially falling asleep. These findings, he said, raise important questions about whether habitual marijuana use is a sustainable strategy for managing sleep problems.

Carole Lieberman, a board-certified psychiatrist in California who also was not affiliated with the study, said it is not surprising that the sleep quality of chronic marijuana users is poor compared to those who do not use it. In her view, people who claim they need marijuana before sleep in order to relax are only kidding themselves; it is more a psychological addiction than a physical one — they enjoy the immediate high, but the marijuana does not help them sleep better.