Persistent lack of sleep ‘may increase risk of future depressive symptoms’

Research shows that consistently sleeping less than 5 hours a night can increase the risk of depression.

Previously, poor sleep was considered a side effect of mental illness, but new research shows that the connection between sleep and mental illness is more complex.

The study, led by UCL researchers, found that people with a stronger genetic predisposition to naps of less than five hours on a given night were more likely to develop symptoms of depression within four to 12 months. year.

But people who are genetically more prone to depression are not more likely to sleep less.

Lead author Odessa Hamilton, UCL Institute of Epidemiology and Healthcare, said: “We have a chicken or the egg scenario between suboptimal sleep time and depression. They often occur simultaneously, but which situation comes first remains largely unresolved.

Using genetic susceptibility to disease, we determined that sleep may precede depressive symptoms and not vice versa.

The researchers used genetic and health data from 7,146 people recruited by the English Longitudinal Study of Aging (ELSA), with an average age of 65.

Analysis of genetic and health data shows that short sleep is linked to the onset of depressive symptoms, like feeling sad or lonely.

Senior author Dr Olesya Ajnakina, UCL Institute of Epidemiology and Healthcare and the Institute of Psychiatry, Psychology and Neuroscience at Kings College London, said: “Short and long sleep duration, along with Depression, are major contributors to the public health burden. highly hereditary.

Polygenic scores, an index of an individual’s genetic tendency toward a trait, are thought to be key to beginning to understand the nature of sleep duration and symptoms of depression.

When looking at the non-genetic association between depressive symptoms and sleep duration, researchers also found that people who slept five hours or less were twice as likely to develop depressive symptoms. ,5 times.

And people who show signs of depression are one-third more likely to be sleep deprived.

Research published in the journal Nature, Translational Psychiatry, also revealed a link between sleeping long and developing depressive symptoms.

According to the findings, people who sleep more than 9 hours are 1.5 times more likely to have depressive symptoms than those who sleep an average of 7 hours.

However, depressive symptoms were not associated with longer sleep 4 to 12 years later, which is consistent with the genetic findings.

Professor Andrew Steptoe, head of Behavioral and Health Sciences, UCL Institute of Epidemiology and Healthcare, said: “Suboptimal sleep and depression increase with age, and with aging population worldwide, the need to better understand the mechanisms involved in depression and depression is increasing. Sleepless.

This study lays an important foundation for future research into the intersection between genetics, sleep, and depressive symptoms.

Study participants slept an average of 7 hours per night.

More than 10% slept less than 5 hours per night at the beginning of the study and increased to more than 15% by the end of the study.

The proportion of people classified as having depressive symptoms increased by about 3 percentage points, from 8.75% to 11.47%.

In the study, data on sleep and depressive symptoms were combined from two Elsa surveys taken two years apart, as sleep duration and depression are known to fluctuate over time.

Sleep duration and depression are both partially inherited from one generation to the next.

Previous studies have shown that depression is about 35% heritable and that genetic differences account for 40% of the differences in sleep duration.