An irregular sleep schedule is associated with more pronounced symptoms of depression, anxiety, and loneliness. Researchers at the University of California, San Francisco and the University of California, San Diego reached this conclusion. The findings were published in the journal Scientific Reports.

The scientists analyzed data from approximately 23,000 people who wore sleep-tracking smart rings for an average of 154 days. The researchers assessed how consistently participants fell asleep and woke up, and compared these measures with monthly surveys of their mental health.

They found that the less consistent the sleep schedule, the more pronounced the symptoms of depression and anxiety. The average Sleep Regularity Index among participants without symptoms of depression was 84 out of 100, compared with 75 among those with severe symptoms. Less regular sleep was also observed among participants who experienced greater feelings of loneliness.

According to the researchers, consistent bedtimes and wake-up times help maintain circadian rhythms — the body's internal biological clock. Disruptions to these rhythms can affect mental health and interfere with the usual timing of meals, physical activity, and light exposure.

However, the scientists emphasize that the relationship may be bidirectional: sleep disturbances can accompany existing psychological problems. Further research is needed to determine whether establishing a regular sleep schedule can improve mental health.