New research has identified functional connectivities in the brain that mediate the association between depressive symptoms and poor sleep quality. The findings were published in JAMA Psychiatry.

“Nowadays depression and sleep problem are two of the most prevalent mental problems. To make matters worse, depression and sleep problems often go hand-in-hand, which has been observed more than a hundred years,” said study author Jianfeng Feng of Fudan University.

About 75% of depressed patients report significant levels of sleep disturbance and people with insomnia also have a higher risk of developing depression.

“However, until now, there was not an efficient way for the treatment of these two problems due to the poor understanding of their underlying mechanism,” Feng explained. “Our research group has worked on depression for more than ten years and produced many significant results. For example, the findings of our previous work published in Brain have shown promise for new treatments.”

“In this work, we tried to figure out what are the brain systems associated with both depression and sleep quality. The answers to this question may lead to better treatments for both depression and sleep, especially for improving the sleep quality of depressive patients.”

The researchers examined data from 1,017 participants who were included in the March 2017 public data release from the Human Connectome Project. They found that both poor sleep quality and depressive symptoms were associated with neural connectivities involving the lateral orbitofrontal cortex, the dorsolateral prefrontal cortex, the cingulate cortex, and the precuneus.

“Our analysis shows that the functional connections between the areas of the brain associated with short-term memory, the self, and negative emotions are increased in both poor sleep and depressive participants. So people with poor sleep or depression may focus too much on the negative things and dwell on bad thoughts, which leads to a poor quality of sleep,” Feng told PsyPost.

The study — like all research — has limitations.

“We only identified the neural connectivity that underlies the association between depression and sleep. There are many interesting and important questions still need to be addressed,” Feng explained.

“For example, the causal relation between sleep and depression is an important topic that deserves much further investigation by using experimental manipulation or treatment administration.”

“Another problem is the treatment of sleep problems and depression,” Feng added. “Future research could examine whether we could improve the symptom of insomnia and depression based on our findings, such as using transcranial magnetic stimulation or transcranial direct current stimulation to stimulate the brain areas identified in this work.”

The study, “Functional Connectivities in the Brain That Mediate the Association Between Depressive Problems and Sleep Quality“, was authored by Wei Cheng, Edmund T. Rolls, Hongtao Ruan, and Jianfeng Feng.