According to the National Institute of Mental Health, approximately 6.7 percent of adults in the United States experience major depressive disorder each year. Women, in particular, are twice as likely as men to experience depression. Therapy and antidepressant medications are common treatments for depression. But can treating insomnia be another route to combating the mood disorder?

Brainy Connection: Insomnia and Depression  

People with insomnia are twice as likely to develop depression compared to those without insomnia. Chronic primary insomnia, which is defined as sleep problems not associated with other health conditions, may increase a person’s risk for depression later in life. So what makes a person with insomnia more susceptible to future depression?

Years of research by John W. Winkelman, MD, PhD, BWH Division of Sleep Medicine, points to a possible answer: brain size.

Winkelman noted that people with depression had a smaller anterior cingulate cortex (ACC), a part of the brain that regulates mood, compared to those without depression. However, those with a familial risk of depression who were not depressed, as well as those with recovered depression, had larger ACCs than those with existing depression.

Winkelman studied the brains of those with insomnia and found an interesting connection between ACC size and depression. He found that those who had primary insomnia (e.g. with insomnia but not depression) had larger ACCs than those with normal sleep. This led the researchers to hypothesize that larger ACCs could be a protective trait against developing depression.

“What we saw is that those with larger ACCs were people at risk for depression because insomnia is a strong risk factor,” said Winkelman. “But these people with larger ACCs never developed depression. These are people with risk but were resilient to the disease.”

The researchers hope that the findings will eventually help clinicians to better identify people with insomnia who may go on to develop depression.

“Perhaps we can identify people with insomnia who are at risk of developing depression later in life. These are the people we want to make sure we treat. If we can intervene and treat their insomnia then perhaps we could prevent them from developing depression later down the road.”

Menopause, Depression and Sleep

For those already struggling with depression, an effective intervention may lie in a better night’s sleep. Hadine Joffe, MD, MSc, director of the Women’s Hormones and Aging Research Program, BWH Department of Psychiatry, is working to build a better understanding of the biological mechanisms behind depression in women.

In a study published in the Journal of Clinical Endocrinology and Metabolism, Joffe and her team detailed how hot flashes, hormones and sleep affected women with menopause-associated depression. Seventy-two peri- and post-menopausal women experiencing depression, hot flashes and sleep disturbance were randomized to receive estradiol (a hormone therapy to treat hot flashes and other menopause symptoms), zolpidem (a medication to treat insomnia), or placebo for eight weeks.

Of the several findings from the study, Joffe observed that for peri- and post-menopausal women, depression symptoms improved when their sleep quality improved, regardless of what treatment they were given.

“The findings are consistent with other studies that have shown that therapies targeting sleep disturbance optimize treatment of depression,” said Joffe. “These particular results show that targeting insomnia in peri- and post-menopausal women may be critical in the overall management of depression.”

According to Joffe, while targeting insomnia in women with menopause-associated depression is a key part of improving mood, antidepressants and psychotherapy remain the primary treatment of depression in these women. However, as seen in other studies of depressed individuals, optimizing sleep plays a fundamental role in achieving full control of depression symptoms and preventing depression recurrence.