People with irregular sleep-wake schedules may experience more severe symptoms of anxiety, depression, and even loneliness, according to a large study led by UC San Francisco and UC San Diego.
Although prior sleep research has largely focused on sleep duration and sleep quality, this study examined sleep regularity — how consistently people followed the same sleep-wake patterns each day — using months of data from wearables.
The study was published in Scientific Reports on Nov. 12.
"Regular sleep and wake time help keep circadian rhythms aligned," said senior author Ashley Mason , PhD, of the UCSF Department of Psychiatry and Behavioral Sciences. "Irregular sleep-wake timing may weaken circadian alignment, which is associated with depression and other mental health disorders."
Irregular sleep schedules can also disrupt the timing of light exposure, meals, exercise, and social activity, all of which help regulate the circadian rhythm, noted Mason, who is also affiliated with the UCSF Osher Center for Integrative Health.
In this study, researchers analyzed data from approximately 23,000 participants who were enrolled in TemPredict, a study launched in 2020 to investigate whether data from wearables could help identify COVID-19 before people recognized symptoms.
Participants contributed an average of 154 days of sleep data, which allowed researchers to examine sleep regularity over time. They also created a "typical week" snapshot to compare their findings with previous, much shorter studies on sleep regularity. They discovered that associations between sleep and mental health were stronger with the longer-term data.
The participants' average age was 46 and just under half were women. They wore a smart ring that uses sensors to detect movement and measure vital signs. The smart ring used this data to estimate when they fell asleep and woke up. Researchers were then able to calculate each participant's Sleep Regularity Index (SRI), ranging from 0 to 100, with higher scores indicating more consistent sleep patterns.
Worsening depression, anxiety tied to progressive sleep irregularity
Participants' depression, anxiety, and loneliness were assessed by a monthly self-reported survey. Overall, less regularly timed sleep correlated with greater depression and anxiety.
In the long-term analysis, participants with few symptoms of depression or none at all had an average SRI of 84, compared with 83 for those with mild depressive symptoms, 81 for moderate symptoms, and 75 for severe symptoms.
Participants with normal levels of anxiety had an average SRI of 84, compared to 79 for those with severe anxiety. Participants with elevated loneliness also had less regular sleep-wake schedules.
"Someone with an SRI of 84 might go to bed and wake up roughly an hour earlier or later than the previous day, on average," said first author Severine Soltani, PhD, formerly of the Bioinformatics and Systems Biology graduate program at UC San Diego. "For someone with an SRI of 75, that shift in sleep schedule might be closer to an hour and a half."
Mason said the association between poor sleep and poor mental health could be codirectional: Irregular sleep could also be explained as a symptom of poor mental health. "Other longitudinal research provides some reason to think that irregular sleep may come first and contribute to later poor health, rather than being solely a consequence of it."
The authors say future research should test whether helping people establish more regular sleep schedules can improve mental health.
Authors: Wendy Hartogensis, MPH, PhD, and Frederick Hecht, MD, from UCSF; Stephan Dilchert, PhD, from City University of New York; and Benjamin Smarr, PhD, from UC San Diego.
Funding: Medical Technology Enterprise Consortium (MTEC) and the U.S. Army Medical Research and Development Command (USAMRDC) under the U.S. Department of Defense. Also #StartSmall Foundation and Oura Health Oy.
Disclosures: Mason has received remuneration for consulting work for Ouraring Inc. Smarr has received remuneration for consulting work and has a financial interest in the company.
About UCSF: The University of California, San Francisco (UCSF) is exclusively focused on the health sciences and is dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. UCSF Health , which serves as UCSF's primary academic medical system, includes top-ranked specialty hospitals and other clinical programs, and has affiliations throughout the Bay Area. UCSF School of Medicine also has a regional campus in Fresno. Learn more at ucsf.edu .
