A wrist monitor spotted poor sleep that people did not feel

A JAMA Network Open cohort study included 1,266 people followed for up to 35 years; 891 also had their sleep measured by a wrist device for one week. Recent and cumulative cannabis use were associated with poorer objective measures, including more fragmentation and more time awake after falling asleep, while participants generally did not report feeling that their sleep was worse. This is an association, not proof of causation: the wristband disagrees with perception but does not make a diagnosis.