A comprehensive new review of studies has warned that daylight saving time may pose serious risks to individuals living with chronic mental illnesses. The seasonal practice of advancing clocks by one hour in spring and returning to standard time in autumn, originally implemented to optimise daylight use, is currently observed in over 70 countries worldwide.
Circadian Disruption and Mental Health
Studies have shown that biannual clock changes can affect the body's natural internal clock, or circadian rhythm, with implications for the health and safety of nearly one billion people who follow the practice. However, research on the exact mental health effects of daylight saving time (DST) has remained fragmented. Scientists from New Mexico State University (NMSU) compiled findings from 60 studies worldwide spanning psychiatry, neuroscience, and public health to consolidate evidence on DST's effects.
The research, published in the journal Brain Sciences, found that the one-hour time shift caused by DST acts as a population-wide circadian stressor. People with depression, bipolar disorder, anxiety disorders, PTSD, ADHD, and psychotic disorders face particularly heightened risks during the days and weeks following a clock change.
Expert Insights
Elizabeth England-Kennedy, assistant professor of public health at NMSU, stated: 'We now have evidence that daylight saving time changes disrupt circadian rhythms in ways that are harmful to people with mental health and sleep-related difficulties.'
Kavita Batra, a study co-author from the University of Nevada, Las Vegas, added: 'We change the clocks in a single night, but the brain does not adjust that quickly. Daylight saving time silently disrupts the body's biological clock, influencing sleep, emotional regulation, cognition, and psychiatric stability.'
Calls to End DST
The findings come amid growing calls to end DST in the US. 'For millions living with chronic mental illness, this is more than lost sleep; it may represent a preventable public health risk or serious exacerbation of existing symptoms,' Dr Batra said.
Researchers noted that DST, particularly spring forward transitions, is associated with increased sleep disturbance, impaired executive functioning, reduced attention and working memory, heightened emotional reactivity, increased depressive symptoms, and elevated risk of manic episodes.
Recommendations for Clinicians
Scientist urge clinicians to treat DST transitions as modifiable risk windows during which they can provide anticipatory guidance to patients on gradually shifting their sleep schedules several days before a clock change. They also suggest prescribing morning bright-light exposure for patients to help realign their natural body rhythms during the weeks around the transitions.
Researchers say permanent standard time, rather than permanent daylight saving time, would better serve public mental health because it more closely aligns with natural morning light exposure and the body's internal clock.
Jagdish Khubchandani, another author of the study from NMSU, commented: 'While more than 100 countries have observed daylight saving time sometime in the past, as of now, only about a third of the world follows this ritual, which offers little value to societal or economic well-being. We could potentially continue to lose millions of dollars due to daylight saving time-related workplace injuries, traffic accidents, and health problems like heart attacks and strokes.'
