The internal biological clock, also known as circadian rhythms, is an internal system that regulates almost all biological and physiological functions in a cycle of approximately 24 hours. This internal clock is present in practically all living organisms, including humans, and affects everything from sleep patterns to the regulation of body temperature, hormone secretion, or digestion. If well synchronized it allows these functions to be performed efficiently and at the appropriate times.
However, the biological clock can easily become imbalanced due to changes in habitual patterns, such as shift work, exposure to artificial light at night, travel that involves a change of time zone and causes jet lag, etc. and these imbalances They can influence sleep quality, mood, and general well-being. New research has now found that imbalances between sleep and the internal biological clock can trigger or intensify various psychiatric disorders.
The study has been carried out by an international team of researchers from the University of Southampton, King’s College London, the University of Bristol and Stanford University, among other institutions, who have reviewed recent evidence focusing on adolescents and young adults with psychiatric disorders. a group particularly vulnerable to the appearance of these disorders and to alterations in sleep and circadian rhythms.
The researchers have published their findings in the Proceedings of the National Academy of Sciences (PNAS) and have highlighted that further understanding of the relationship between sleep, circadian rhythms and mental health could open the door to comprehensive treatments to mitigate psychiatric problems. .
“Sleep and circadian rhythm disturbances are more common than we think in all types of psychiatric disorders,” says Dr. Sarah L. Chellappa, from the University of Southampton and lead author of the study. “Although the impact of insomnia on the development and maintenance of these disorders is known, we still need to understand how circadian disturbances influence it.” “It is crucial to understand how these factors interact to develop interventions that improve both patients’ sleep and mental health symptoms,” she adds.
Insomnia and hypersomnia: more common in people with mental problems
Insomnia has been observed to be more common in people with mental health disorders than in the general population, especially during acute episodes and at the onset of psychosis, where more than half of individuals have difficulty falling and staying asleep. . Additionally, between a quarter and a third of people with mood disorders suffer from both insomnia and hypersomnia, which involves difficulty sleeping at night and daytime sleepiness. A similar proportion is observed in people with psychosis.
Additionally, studies on circadian sleep-wake disorders (CRSWD) indicate that 32% of patients with bipolar disorder sleep and wake up later than normal (known as Delayed Sleep-Wake Phase Disorder). It has been reported that biological clock processes, such as endogenous cortisol rhythms, advance seven hours during manic episodes and are delayed four to five hours in the depressive phase. The rhythm normalizes with successful treatment.
“Variability in sleep duration and timing can cause a mismatch between our biological clock and our sleep-wake rhythms, increasing the risk of sleep disorders and negative consequences on mental health”
The researchers analyzed the possible mechanisms behind sleep-circadian disturbances in individuals with psychiatric disorders. During adolescence, physiological changes in sleep patterns are combined with behavioral changes, such as going to bed later and sleeping less during school days and more on weekends.
Dr. Nicholas Meyer, from King’s College London and co-author of the study, explained: “This variability in sleep duration and timing can cause a mismatch between our biological clock and our sleep-wake rhythms, increasing the risk of sleep disorders. sleep and negative consequences on mental health.
The researchers also examined the role of genes, light exposure, neuroplasticity and other factors. Those with a genetic predisposition to reduced changes in activity levels between rest and wake phases are more likely to experience depression, mood instability, and neuroticism. Population-level surveys show that reported time outdoors is associated with a lower likelihood of mood disorders. Sleep is thought to play a key role in forming new neural connections and processing emotional memories.
Improve sleep to prevent and treat mental disorders
Dr. Renske Lok of Stanford University and co-author of the study noted that “targeting sleep and circadian risk factors offers the opportunity to develop new preventive measures and therapies. Some of these are population-level considerations, such as school and work schedules, or changes in the environment aimed at optimizing light exposure. Others are personalized interventions tailored to individual circadian parameters.”
Cognitive Behavioral Therapy for Insomnia (CBT-I) has been shown to reduce symptoms of anxiety and depression, as well as symptoms of trauma in people with post-traumatic stress disorder (PTSD). In unipolar and bipolar depression, light therapy (applied upon rising in the morning) was effective compared to a placebo. Using it in combination with medication was also more effective than medication alone. Other findings suggest that light is effective in treating perinatal depression.
The timing of medications, meals, and exercise may also influence circadian phases. Taking melatonin at night may help people with sleep-wake delay syndrome advance their biological clock toward a more conventional sleep pattern and may have beneficial effects on comorbid psychiatric disorders. Working at night can negatively affect mental health, but eating during the day instead of at night could help, as studies show that eating during the day prevents mood decline.
The study also highlights innovative multidisciplinary interventions, such as the Transdiagnostic Intervention for Sleep and Circadian Dysfunction (Trans-C), which combines modules addressing different aspects of sleep and circadian rhythms in a sleep health framework applicable to a variety of mental disorders. “Taken together, mental health research is poised to take advantage of extraordinary advances in sleep and circadian science and translate these into better understanding and treatment of psychiatric disorders,” concludes Dr. Chellappa.
