A large international study based on data from 22,894 adults has found that irregular sleep-wake patterns are associated with more severe symptoms of depression, anxiety and loneliness, even when age, sex and average sleep duration are taken into account. Researchers analysed data collected in 2020 through the TemPredict project, in which participants wore an Oura Ring smart device to record when they fell asleep and woke up. The work, published in Scientific Reports, adds to growing evidence that consistency of sleep timing may matter alongside the number of hours slept, although the authors caution that the findings do not prove cause and effect.
Key Takeaways: The study covered 22,894 adults and an average of 154 days of sleep data per participant. People with no or mild depressive symptoms had a sleep regularity index of 83.74, compared with 74.93 among those with severe symptoms; a five-point lower score was linked to about 46% higher odds of severe depression and 29% higher odds of severe anxiety. The researchers stress that the results concern symptom assessments, not confirmed clinical diagnoses.
Sleep and wakefulness are governed by an internal biological clock that controls daily rhythms. The sleep regularity index is higher when a person is in the same state — asleep or awake — at the same time across different days. Previous research has focused heavily on sleep duration and quality, but the new findings suggest that the stability of sleep timing is also important. If someone goes to bed early on workdays and stays up until the middle of the night at weekends, their usual sleep pattern may be disrupted.
For the analysis, researchers at the University of California compared full multi-month records with a single week of data, including a period before Covid-19 restrictions. The multi-month data showed stronger associations than the one-week analysis. People with severe anxiety had an index of 78.94, compared with 83.67 among those without noticeable symptoms. Those who reported stronger loneliness also tended to have less regular sleep schedules.
The authors suggest that disrupted sleep schedules may disturb circadian function and alter how light, meal timing and physical activity affect the body. But reverse causality is also possible: anxiety or low mood can make it harder to fall asleep on time. The study therefore cannot establish a clear direction of cause and effect, and it assessed symptoms rather than doctor-confirmed diagnoses.
The findings indicate that mental-health assessments should consider sleep regularity as well as sleep duration. It remains unclear whether maintaining a consistent sleep schedule can reduce symptoms of depression and anxiety. Further research, including trials of behavioural programmes to stabilise sleep timing, will be needed to answer that question.
Source: kun.uz