A study of about 23,000 people found that less-consistent sleep schedules were associated with more severe symptoms of depression, anxiety and loneliness. The research, published Nov. 12 in the journal Scientific Reports, examined participants’ sleep patterns over extended periods rather than relying on a single night of data.
The participants provided an average of 154 days of sleep information for a project that originally examined whether wearable devices could help identify COVID-19 before symptoms appeared. Researchers compared the sleep data with monthly surveys in which participants reported symptoms related to depression, anxiety and loneliness.
How sleep regularity was measured
The research team calculated a Sleep Regularity Index, or SRI, for each participant. The score ranges from 0 to 100, with higher scores representing more consistent times for falling asleep and waking up.
- Participants with severe depression symptoms had an average SRI of 75, compared with 84 among those reporting few or no symptoms.
- Those with severe anxiety had an average SRI of 79, compared with 84 among participants with normal anxiety levels.
- Participants reporting higher levels of loneliness had an average SRI of 82, compared with 84 among those reporting less loneliness.
The differences were also observed with relatively small changes in sleep timing. Researchers found that variation of about 30 minutes in when a person typically sleeps and wakes can be associated with differences in mood. The findings describe a relationship between sleep regularity and mental-health symptoms; they do not establish that an irregular schedule causes depression, anxiety or loneliness.
Researchers said inconsistent sleep timing can affect several daily patterns at once, including exposure to sunlight, meal timing, exercise and social activity. Those routines influence the body’s circadian rhythm, the internal timing system that helps organize sleep and other biological processes.
Ashley Mason, senior researcher and director of the University of California, San Francisco’s Sleep, Eating, Affect Laboratory, said consistent sleep and wake times help keep circadian rhythms aligned. She said irregular timing may weaken that alignment, which is associated with depression and other mental-health disorders.
What the study adds
Because the study used repeated wearable-device measurements and monthly surveys, researchers could compare longer-term sleep patterns with reported symptoms. The participants were not evaluated through a clinical diagnosis in the information provided, and the findings are based on associations in the study data.
For college students and other young adults whose schedules can change across classes, work, social activities and weekends, the study focuses on the timing of sleep as well as the amount of sleep. The researchers’ findings identify regularity as one factor connected with mental health, alongside the daily routines that help regulate the body’s internal clock.
