A new study may help shed light on why so many people with depression suffer from poor sleep.

Researchers from the University of Warwick (UK) and Fudan University (China) found a strong connection between the areas of the brain associated with short-term memory, one’s sense of self, and negative emotions in people with depression. This association can cause sufferers to dwell on bad thoughts and potentially lead to impaired sleep quality.

“The relation between depression and sleep has been observed more than 100 years, and now we have identified the neural mechanisms of how they are connected for the first time,” said Professor Jianfeng Feng from the University of Warwick’s Department of Computer Science.

The study opens up the possibility for new targeted treatments and may lead to better sleep quality for people with depression.

Depression and sleep problems often go hand-in-hand. About 75 percent of depressed patients report significant levels of sleep disturbance, such as difficulty falling asleep and short duration of sleep (insomnia). People with insomnia also have a greater risk of developing depression and anxiety than those with normal levels of sleep.

For the study, the research team analyzed data from around 10,000 people to investigate the neural mechanisms underlying the link between depression and quality of sleep.

In the brains of those with depression, the researchers discovered a strong connection between the dorsolateral prefrontal cortex (associated with short-term memory), the precuneus (associated with the self) and the lateral orbitofrontal cortex (associated with negative emotion).

The researchers conclude that increased functional connectivity between these brain regions provides a neural basis for how depression is related to poor sleep quality.

“This important cross-validation with participants from the USA provides support for the theory that the lateral orbitofrontal cortex is a key brain area that might be targeted in the search for treatments for depression,” said Professor Edmund Rolls from Warwick’s Department of Computer Science.

Feng noted the findings could have important public health implications, as both sleep problems and depression impact a large number of people.

“In today’s world, poor sleep and sleep deprivation have become a common problem affecting more than a third of the world’s population due to longer work hours and commuting times, later night activity, and increased dependency on electronics,” said Feng. “The disorder of insomnia has become the second most prevalent mental disorder.”

“And major depressive disorder is also ranked by the World Health Organization as the leading cause of years-of-life lived with disability. According to a recent statistic, it affects approximately 216 million people (3 percent of the world’s population). So almost everyone in the world is related to these two problems, as a sufferer or a relative of a sufferer.”

Source: University of Warwick