The relationship between disordered sleep and emotional health is an intricate one, as each can influence the other for better and worse. Stress and worry, as well as mental illnesses such as depression and anxiety can interfere with sleep. And an abundance of research indicates that people who experience disrupted sleep, including obstructive sleep apnea and insomnia, are at dramatically elevated risk for depression and other psychiatric disorders. Insomnia is an important risk factor for depression, and has also been linked to a sharply increased risk of suicide among people who suffer from depression. Despite all that we know about this complicated relationship, scientists are still working to understand the underlying mechanics and root causes of sleep disorders and mood disorders when both are present.
A new study provides some important new information about how disrupted, insufficient sleep may contribute to the onset of emotional difficulties as well as the development of depression and other psychiatric problems. Researchers at the University of Pittsburgh School of Medicine investigated emotional responses in the brains of people with insomnia and found dysfunctional activity in an area of the brain that regulates and processes emotions. Their findings may provide an explanation for the mechanism by which disrupted sleep influences depression and other psychiatric conditions.
Researchers included 44 adults in their study. Of these, 14 had chronic insomnia, and no other primary psychiatric disorders. The remaining 30 participants were people who had no insomnia and who slept well. All of the study subjects participated in the same exercise, a task involving voluntary emotional regulation. First, participants were shown a series of images containing both negative and neutral emotional content. They were asked to view the series of images passively, without trying to control or influence their emotional responses. When they were shown the images a second time, participants were asked to decrease their emotional response using a voluntary emotional regulation technique called cognitive reappraisal. Cognitive reappraisal involves the deliberate attempt to change one’s emotional response to a stimulus. In this case, participants were asked to intentionally decrease their negative emotional responses to the images shown to them. Researchers’ analysis showed:
- A distinct difference in the brain activity of those with insomnia compared to those with normal sleep patterns. Specifically, researchers found a dramatic difference in the activity of the amygdala, a cluster of neurons within the temporal lobe that plays a critical role in processing and regulating emotion.
- Amygdala activity was significantly greater for those with insomnia during the period when they were asked to decrease their negative responses to images using cognitive reappraisal, compared to those without the sleep disorder.
- There was no significant difference between insomnia and non-insomnia participants during their passive viewing of the images.
Previous research has shown that cognitive reappraisal decreases amygdala activity. These results, which show the opposite, suggest that insomnia may impair the brain’s ability to successfully process negative emotions, a finding that could help to explain the mechanics of how sleep contributes to depression and other psychiatric disorders.
Other recent research has demonstrated evidence of neural changes and emotional regulation difficulties among people with disordered, insufficient sleep:
- The ability to accurately judge emotion in human faces is compromised by sleep deprivation, according to research conducted at the University of California, Berkeley. Researchers measured the ability to read emotions in faces by people who were sleep deprived in a laboratory setting, and found significant impairment to their assessment of certain emotions, including anger and sadness. The impairment was particularly significant among women. The decrease in this ability was alleviated after a night of recovery sleep.
- Researchers in the United Kingdom examined how sleep deprivation affects inhibition and impulse control. They found a night of sleep deprivation lowered inhibition and increased impulsivity to negative stimuli.
- In responding to a series of images categorized as pleasant, neutral, or unpleasant, people who were sleep deprived perceived the neutral images more negatively than those who were not sleep deprived. Those who were sleep deprived also demonstrated more negative moods.
- Sleep deprived patients were more highly reactive to both negative and positive stimuli, showing greater levels of activity in the limbic regions of the brain, where much of the work of emotional regulation and processing occurs.
The latest research findings add to the growing body of scientific knowledge indicating that sleep problems cause dysfunction in the brain that may contribute to emotional difficulties and psychiatric conditions. This is an exciting and important area of research, as scientists continue to explore the biological roots of both sleep disorders and psychiatric disorders.
All of us who’ve experienced insufficient, disrupted sleep know first-hand how being sleep deprived can negatively affect our emotional equilibrium. When we’re tired, we’re more likely to be short-tempered, impatient, and moody. Research such as this brings us closer to understanding the mechanics that may underlie a broad range of emotional disturbance and dysfunction.
Michael J. Breus, PhD
The Sleep Doctor®