A lack of sleep, which is common in anxiety disorders, may play a key role in firing up brain regions that contribute to excessive worrying.
Sleep deprivation amplifies anticipatory anxiety by activating the brain’s amygdala and insular cortex regions associated with emotional processing.
The resulting pattern mimics the abnormal neural activity seen in anxiety disorders.
Furthermore, research suggests that innate worriers people who are naturally more anxious and therefore more likely to develop a full-blown anxiety disorder are acutely vulnerable to the effect of insufficient sleep.
“These findings help us realize that those people who are anxious by nature are the same people who will suffer the greatest harm from sleep deprivation,” says Matthew Walker, professor of psychology and neuroscience at the University of California, Berkeley.
The results suggest that people suffering from such maladies as generalized anxiety disorder, panic attacks, and post-traumatic stress disorder, may benefit substantially from sleep therapy.
“If sleep disruption is a key factor in anxiety disorders, as this study suggests, then it’s a potentially treatable target,” Walker says. “By restoring good quality sleep in people suffering from anxiety, we may be able to help ameliorate their excessive worry and disabling fearful expectations.”
While previous research has indicated that sleep disruption and psychiatric disorders often occur together, this latest study, published in the Journal of Neuroscience, is the first to causally demonstrate that sleep loss triggers excessive anticipatory brain activity associated with anxiety.
“It’s been hard to tease out whether sleep loss is simply a byproduct of anxiety, or whether sleep disruption causes anxiety,” says Andrea Goldstein, a doctoral student in psychology and lead author of the study. “This study helps us understand that causal relationship more clearly.”
In their experiments, researchers scanned the brains of 18 healthy young adults as they viewed dozens of images, first after a good night’s rest, and again after a sleepless night. The images were neutral, disturbing, or alternated between both.
Participants in the experiments reported a wide range of baseline anxiety levels, but none fit the criteria for a clinical anxiety disorder. After getting a full night’s rest at the lab, which researchers monitored by measuring neural electrical activity, their brains were scanned via functional MRI as they waited to be shown, and then viewed 90 images during a 45-minute session.
To trigger anticipatory anxiety, researchers primed the participants using one of three visual cues prior to each series of images. A large red minus sign signaled to participants that they were about to see a highly unpleasant image, such as a death scene. A yellow circle portended a neutral image, such as a basket on a table.
Perhaps most stressful was a white question mark, which indicated that either a grisly image or a bland, innocuous one was coming, and kept participants in a heightened state of suspense.
When sleep-deprived and waiting in suspenseful anticipation for a neutral or disturbing image to appear, activity in the emotional brain centers of all the participants soared, especially in the amygdala and the insular cortex. Notably, the amplifying impact of sleep deprivation was most dramatic for those people who were innately anxious to begin with.
“This discovery illustrates how important sleep is to our mental health,” says Walker. “It also emphasizes the intimate relationship between sleep and psychiatric disorders, both from a cause and a treatment perspective.”
The National Institute of Mental Health funded the research.