Study links cannabis use to worse wristband-measured sleep
Northwestern researchers found more nighttime waking in people who used cannabis over 35 years of follow-up, although they did not notice a difference in their own rest.
Researchers at Northwestern University reported on Oct. 9, in JAMA Network Open, a study in which cannabis use appears tied to more interrupted sleep. The difference comes from a wristband, not from participants' own answers about how they rest.
The data come from CARDIA, a cohort that has followed adults in four U.S. cities since 1985-86. Their cannabis use was recorded over 35 years. In the final year, 891 people wore an actigraphy wristband for seven days and answered a sleep-quality questionnaire. Their average age was 60.7.
What the wristband measured
Each accumulated year of use was associated with an odds ratio of 1.21 for prolonged awakenings of 30 minutes or more. People who had used cannabis in the previous 30 days had an odds ratio of 3.23 for those awakenings compared with people who never used it, and spent 11.09 more minutes awake after falling asleep. They were also more likely to sleep more than eight hours, with an odds ratio of 4.60.
There was no association with the sleep participants reported themselves. People who had stopped using cannabis did not differ from people who never used it on any objective measure.
What the study does not say
It is an observational cohort: it shows an association and does not demonstrate that cannabis causes fragmented sleep. Use was self-reported and does not distinguish potency or method. Sleep was measured only once, over one week, so it is not known what came first. The authors note that cannabis potency has changed over three decades and that the results may not apply to young people or to stronger products. Funding came from contracts and grants of the U.S. heart, lung and blood institute.
The American Academy of Sleep Medicine earlier summarized a report by the U.S. National Academies that saw moderate evidence of a short-term benefit of cannabinoids for sleep in specific conditions such as chronic pain. The populations, products and timeframes differ, and the results are not comparable.
The findings describe middle-aged adults in a U.S. cohort, a specific group, and are not a guide for the general population. People with trouble sleeping can consult a health professional.
