Washington: According to a new genetic study headed by UCL (University College London) experts, sleeping less than five hours per night may increase the risk of getting depressive symptoms. Historically, poor sleep has been seen as a side effect of mental ill health, but this study found that the link between sleep and mental illness is more complex. The study, published in the journal Translational Psychiatry, analysed data from people with an average age of 65 and found short sleep was associated with the onset of depressive symptoms.
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Lead author Odessa S. Hamilton (UCL Institute of Epidemiology & Health Care) said: “We have this chicken or egg scenario between suboptimal sleep duration and depression, they frequently cooccur, but which comes first is largely unresolved. Using genetic susceptibility to disease we determined that sleep likely precedes depressive symptoms, rather than the inverse.”
For the study, the researchers used genetic and health data from 7,146 people recruited by the English Longitudinal Study of Ageing (ELSA), a nationally representative population study in England.
They found that people with a stronger genetic predisposition to short sleep (less than five hours in a given night) were more likely to develop depressive symptoms over 4-12 years, but that people with a greater genetic predisposition to depression did not have an increased likelihood of short sleep.
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Senior author Dr Olesya Ajnakina (UCL Institute of Epidemiology & Health Care and the Institute of Psychiatry, Psychology & Neuroscience at King’s College London) said: “Short and long sleep durations, along with depression, are major contributors to public health burden that are highly heritable. Polygenic scores, indices of an individual’s genetic propensity for a trait, are thought to be key in beginning to understand the nature of sleep duration and depressive symptoms.”
The researchers assessed the strength of genetic predisposition among the ELSA participants using findings from previous genome-wide association studies that have identified thousands of genetic variants linked to a higher likelihood of developing depression and short or long sleep.
As part of a number of separate analyses to investigate the robustness of their results, the research team also looked at non-genetic associations between depressive symptoms and sleep duration.
They found that people sleeping five hours or less were 2.5 times more likely to develop depressive symptoms, while people with depressive symptoms were a third more likely to suffer from short sleep. They adjusted for a rich selection of factors that could affect the results such as education, wealth, smoking status, physical activity and limiting longstanding illness.
The researchers also found a link between sleeping long and developing depressive symptoms, with participants sleeping longer than nine hours being 1.5 times more likely to develop depressive symptoms than those who sleep an average of seven hours. However, depressive symptoms were not associated with sleeping longer four to 12 years later, which corresponded to the genetic findings.
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Professor Andrew Steptoe (Head of Behavioural Science and Health, UCL Institute of Epidemiology & Health Care) said,
Suboptimal sleep and depression increase with age, and with the worldwide phenomenon of population ageing there is a growing need to better understand the mechanism connecting depression and a lack of sleep. This study lays important groundwork for future investigations on the intersection of genetics, sleep, and depressive symptoms.
Overall, the participants in the study had an average of seven hours’ sleep a night. More than 10% slept for less than five hours a night at the start of the study period, rising to over 15% at the end of the study period, and the proportion of participants classed as having depressive symptoms increased by ~3 percentage points, from 8.75-11.47 per cent.
Both sleep duration and depression are partly inherited from one generation to the next. Earlier twin studies have suggested depression is about 35% heritable, and that genetic differences account for 40% of the variance in sleep duration.
In the study, data on sleep and depressive symptoms were combined from two ELSA surveys conducted two years apart, as sleep duration and depression are known to fluctuate over time.
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(This story has not been edited by NDTV staff and is published from a syndicated feed.)
NDTV – Dettol have been working towards a clean and healthy India since 2014 via the Banega Swachh India initiative, which in its Season 10 is helmed by Campaign Ambassador Ayushmann Khurrana. The campaign aims to highlight the inter-dependency of humans and the environment, and of humans on one another with the focus on One Health, One Planet, One Future – Leaving No One Behind. It stresses on the need to take care of, and consider, everyone’s health in India – especially vulnerable communities – the LGBTQ population, indigenous people, India’s different tribes, ethnic and linguistic minorities, people with disabilities, migrants, geographically remote populations, gender and sexual minorities. In a world post COVID-19 pandemic, the need for WASH (Water, Sanitation and Hygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign will continue to raise awareness on the same along with focussing on the importance of nutrition and healthcare for women and children, fight malnutrition, mental well-being, self-care, science and health, adolescent health & gender awareness. Along with the health of people, the campaign has realised the need to also take care of the health of the eco-system. Our environment is fragile due to human activity, which is not only over-exploiting available resources, but also generating immense pollution as a result of using and extracting those resources. The imbalance has also led to immense biodiversity loss that has caused one of the biggest threats to human survival – climate change. It has now been described as a “code red for humanity.” The campaign will continue to cover issues like air pollution, waste management, plastic ban, manual scavenging and sanitation workers and menstrual hygiene. Banega Swasth India will also be taking forward the dream of Swasth Bharat, the campaign feels that only a Swachh or clean India where toilets are used and open defecation free (ODF) status achieved as part of the Swachh Bharat Abhiyan launched by Prime Minister Narendra Modi in 2014, can eradicate diseases like diahorrea and the country can become a Swasth or healthy India.
