Exploring the connection between sleep, body clock, and mental health

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

The review, published on 19 February 2024 in Proceedings of the National Academy of Sciences (PNAS), suggests gaining a better understanding of the relationship between sleep, circadian rhythms and mental health could unlock new holistic treatments to alleviate mental health problems.

“Sleep-circadian disturbances are the rule, rather than the exception, across every category of psychiatric disorders,” says Dr Sarah L. Chellappa from the University of Southampton and 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.”

Insomnia is more common in people with mental health disorders than in the general population. Around 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.

Another study suggests that 32 per cent of patients with bipolar disorder go to sleep and wake later than usual (a condition called Delayed Sleep-Wake Phase Disorder). Body clock processes (such as endogenous cortisol rhythms) have been reported to run seven hours ahead during manic episodes and four to five hours behind during the depressive phase.

Researchers from the University of Southampton, Kings College London, Stanford University, and other institutions delved into recent findings on sleep and circadian influences, specifically focusing on adolescents and young adults with psychiatric disorders. This age group is particularly vulnerable to mental health issues and disruptions in sleep and circadian rhythms. The study explored various factors contributing to these disturbances, including genetic predispositions, light exposure, and neuroplasticity.

The study’s findings suggest that individuals with genetic variations affecting activity levels during rest and wake phases are more susceptible to depression and mood instability. Additionally, population-level surveys indicate that spending time outdoors is associated with a lower likelihood of mood disorders. Sleep is believed to play a crucial role in neural connectivity and emotional memory processing. Using it in combination with medication was also more effective than using medication alone. 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.

“The 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,” said Dr Nicholas Meyer, from King's College London, co-lead of the review.

Reference: DOI: 10.1073/pnas.2214756121