The Annex: about 23,000 smart rings, 154 nights each, and a sleep score that slips from 84 to 75 as depression deepens

The Annex reads the method behind the headline. Today’s: a study led by UC San Francisco and UC San Diego, published in Scientific Reports on 12 November, which asks whether people who go to bed and get up at irregular times report more depression, anxiety and loneliness¹. Most sleep research looks at how long and how well people sleep; this one looks at regularity¹.

The design. About 23,000 participants from TemPredict, a study launched in 2020 to see whether wearables could flag COVID-19 before symptoms, wore a smart ring that estimated when they fell asleep and woke¹. They contributed an average of 154 days of sleep data¹. From that, the team calculated a sleep regularity index (SRI) from 0 to 100, higher meaning more consistent¹. Depression, anxiety and loneliness came from a monthly self-reported survey¹. The average participant was 46, and just under half were women¹. The team also built a “typical week” snapshot to compare with earlier, much shorter studies, and found the associations were stronger in the longer-term data¹.

The result. A clean gradient. People with few or no depressive symptoms averaged an SRI of 84; mild symptoms, 83; moderate, 81; severe, 75¹. On anxiety, 84 for normal levels against 79 for severe¹. Elevated loneliness also went with less regular schedules¹. In plain terms, first author Severine Soltani says an SRI of 84 means bed and waking times roughly an hour earlier or later than the day before, on average; at 75, closer to an hour and a half¹.

The footnote that matters. This is an association, and the senior author, Ashley Mason, says the link “could be bidirectional”: irregular sleep may also be a symptom of poor mental health¹. She points to other longitudinal work suggesting irregular sleep may come first, but this paper does not settle it, and the authors’ stated next step is to test whether making schedules more regular actually helps¹. Note too who was measured: ring wearers who signed up for a pandemic study, scoring their own symptoms.

For you. The cheap, reversible part is already in your hands: roughly the same bedtime and the same alarm, weekends included. Treat it as good housekeeping rather than a cure, and if your mood has slipped along with your sleep, the right next step is still a conversation with your GP.