Study links cannabis use to worse sleep

A study published in JAMA Network Open on October 9, 2026 by Thanh-Huyen Vu from Northwestern University found that cumulative cannabis consumption over the years correlates with deteriorating sleep quality.

Long-term tracking of participants

The study followed participants from their 20s for 35 years, using wrist sensors to measure sleep during a one-week period at an average age.

Participants from diverse background

The research involved 1,266 participants from the CARDIA cohort, which has tracked Black and White adults in the United States since 1985.

Cannabis use and sleep patterns

Participants were asked about their cannabis consumption multiple times and completed questionnaires on their perceived sleep quality, allowing researchers to compare subjective feelings with objective measurements.

Findings on sleep efficiency

The study found that as cumulative cannabis use increases, sleep efficiency decreases, measured by the ratio of actual sleep time to time spent in bed. Sleep also becomes more fragmented, with increased wakefulness periods.

No perceived change in sleep quality

However, no causal relationship was established, and users did not perceive any difference in their sleep quality.