How lack of sleep is linked to depressive symptoms

It’s well-known that adequate sleep is crucial for good health and a lack of it can lead to various health issues including hypertension and cardiovascular diseases. Now, a new study shows that consistently sleeping less than five hours a night might increase the risk of developing depressive symptoms.

The study, led by researchers from the University College of London, found that among people with an average age of 65, short sleep was associated with the onset of depressive symptoms. Furthermore, those who had a stronger genetic predisposition to short sleep— referred to less than five hours in one night— were more likely to develop depressive symptoms over four to 12 years, the university’s press statement explains.

“Using genetic susceptibility to disease we determined that sleep likely precedes depressive symptoms, rather than the inverse,” explains lead author Odessa S. Hamilton. The findings were published in Translational Psychiatry.

Along with depression, short and long sleep durations, are major contributors to public health burden that can be passed on across generations, the statement added. Polygenic scores, the measure of an individual’s genetic propensity for a trait, are believed to be key to understanding the nature of sleep duration and depressive symptoms.

According to the statement, the researchers also found that people sleeping five hours or less were 2.5 times more likely to develop depressive symptoms and those with depressive symptoms were a third more likely to suffer from short sleep. Moreover, participants sleeping longer than nine hours were 1.5 times more likely to develop depressive symptoms compared to those sleeping an average of seven hours.

“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,” explains study author, Andrew Steptoe in the statement. The findings are important to understand how genetics, sleep and depressive symptoms could be related.

Adequate sleep is not only important for good mental and physical well-being but can also reduce gains made during wake hours. Another study by UCL researchers, published in the journal The Lancet Health Longevity in July, shows that people who were more physically active but had short sleep experienced faster cognitive decline overall.