Sleep problems can trigger mental illness, study finds

Problems with our sleep and internal body clock can trigger or worsen a range of psychiatric disorders, according to a new review of research.

The review, published in the Proceedings of the National Academy (PNAS), suggests that if we gain a better understanding of the relationship between sleep, circadian rhythms and mental health, we could develop new treatments to address mental health problems.

The study was carried out by an international team of researchers from the University of Southampton, the University of Bristol, King’s College London, Stanford University and other institutions. It explored recent evidence on sleep and circadian factors, focusing on adolescents and young adults with psychiatric disorders.

“Sleep-circadian disturbances are the rule, rather than the exception, across every category of psychiatric disorders,” said Dr Sarah Chellappa from the University of Southampton, senior author of the review. “Sleep disturbances, such as insomnia, are well understood in the development and maintenance of psychiatric disorders, but our understanding of circadian disturbances lags behind.

“It is important to understand how these factors interact so we can develop and apply sleep-circadian interventions that benefit the sleep and mental health symptoms of patients.”

People with psychosis are more likely to have difficulty sleeping

Insomnia is more common in people with mental health disorders than in the general population. Difficulty falling and staying asleep affects over half of people in the early stages of psychosis. About a quarter to a third of people with mood disorders have both insomnia and hypersomnia, where patients find it hard to sleep at night, but are sleepier in the daytime. Similar proportions of people with psychosis experience this combination of sleep disorders.

Meanwhile, the few studies looking at circadian rhythm sleep-wake disorders (CRSWD) suggest that 32% of patients with bipolar disorder go to sleep and wake later than usual (a condition called Delayed Sleep-Wake Phase Disorder). Body clock processes have been reported to run seven hours ahead during manic episodes and four-to-five hours behind during the depressive phase.

The researchers looked at the possible mechanisms behind sleep-circadian disturbances in psychiatric disorders. During adolescence, physiological changes in how we sleep combine with behavioural changes, such as staying up later, getting less sleep on school nights and sleeping in on weekends.

Dr Nicholas Meyer, from King’s College London, who co-led the review, said: “This variability in the duration and timing of sleep can lead to a misalignment between our body clock, and our sleep-wake rhythms can increase the risk of sleep disturbances and adverse mental health outcomes.”

Sleep plays a role in forming neural connections

Researchers also looked at the role of genes, exposure to light, neuroplasticity and other possible factors. Those with a genetic predisposition towards a reduced change in activity levels between rest and wake phases are more likely to experience depression, mood instability and neuroticism. Population-level surveys show self-reported time outdoors was associated with a lower probability of mood disorder. Sleep is thought to play a key role in how the brain forms new neural connections and processes emotional memories

The timing of medication, meals and exercise could also impact circadian phases. Taking melatonin in the evening can help people with Delayed Sleep-Wake Phase Disorder to shift their body clock forward towards a more conventional sleep pattern, and may have beneficial effects in comorbid psychiatric disorders. Nightshift work can adversely affect mental health, but eating in the daytime rather than during the night could help, with research showing daytime eating prevents mood impairment.

Matt Jones, professor in at the University of Bristol, added: “Many current treatments for psychiatric disorders are based on one-size-fits-all, trial-and-error approaches. Understanding the sleep and circadian patterns of individuals living with these disorders offers exciting opportunities for early intervention and the precisely tailored therapies people deserve.  New, wearable devices able to accurately measure these sleep and circadian patterns across long timescales should really help bring this precision to psychiatry.”