When the Clock Shifts: A Comprehensive Review of Daylight-Saving Time (DST), Circadian Disruption, and...

Daylight Saving Time (DST) creates abrupt, externally imposed circadian disruptions that can impair sleep regulation, hormonal balance, cognitive performance, and emotional stability. Although these effects are known in the general population, individuals with chronic mental illness, whose circadian systems are often intrinsically dysregulated, may face increased neuropsychological consequences. This comprehensive review synthesizes evidence from chronobiology, psychiatry, neuroscience, and population health to examine how DST-related circadian misalignment impacts cognitive functioning, mood regulation, suicidality risk, and symptom exacerbation across psychological disorders such as depression, anxiety disorders, bipolar disorder, post-traumatic stress disorder, attention-deficit/hyperactivity disorder, and psychotic disorders. Following the Scale for the Assessment of Narrative Review Articles (SANRA) guidelines, a search of PubMed, PsycINFO, Scopus, and Google Scholar was conducted to identify studies published from 2000-2026 examining DST, circadian rhythm disruption, neuropsychological outcomes, and chronic mental illness. Empirical, theoretical, and mechanistic studies were included to ensure comprehensive synthesis. Across conditions, 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, elevated risk of manic episodes, and short-term increases in suicidality. Neurobiological mechanisms include altered melatonin secretion, cortisol dysregulation, Hypothalamus Pituitary Axis (HPA-axis) activation, and clock-gene desynchrony. DST may function as a modifiable negative environmental influence capable of affecting neuropsychological functioning in vulnerable populations. These findings underscore the need for clinical awareness, preventive strategies, and policy reconsiderations, including calls to eliminate seasonal time changes. Standardizing DST-related research outcomes and expanding longitudinal, multi-site studies will be essential for advancing this emerging field.