Stressed to the max? deep sleep can rewire the anxious brain

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WHEN it comes to managing anxiety disorders, William Shakespeare’s Macbeth had it right when he referred to sleep as the “balm of hurt minds.” While a full night of slumber stabilizes emotions, a sleepless night can trigger up to a 30% rise in anxiety levels, according to new research from the University of California, Berkeley.
UC Berkeley researchers have found that the type of sleep most apt to calm and reset the anxious brain is deep sleep, also known as non-rapid eye movement (NREM) slow-wave sleep, a state in which neural oscillations become highly synchronized, and heart rates and blood pressure drop.
“We have identified a new function of deep sleep, one that decreases anxiety overnight by reorganizing connections in the brain,” said study senior author Matthew Walker, a UC Berkeley professor of neuroscience and psychology. “Deep sleep seems to be a natural anxiolytic (anxiety inhibitor), so long as we get it each and every night.”
The findings, published today, Nov. 4, in the journal Nature Human Behaviour, provide one of the strongest neural links between sleep and anxiety to date. They also point to sleep as a natural, non-pharmaceutical remedy for anxiety disorders, which have been diagnosed in some 40 million American adults and are rising among children and teens.
“Our study strongly suggests that insufficient sleep amplifies levels of anxiety and, conversely, that deep sleep helps reduce such stress,” said study lead author Eti Ben Simon, a postdoctoral fellow in the Center for Human Sleep Science at UC Berkeley.
In a series of experiments using functional MRI and polysomnography, among other measures, Simon and fellow researchers scanned the brains of 18 young adults as they viewed emotionally stirring video clips after a full night of sleep, and again after a sleepless night. Anxiety levels were measured following each session via a questionnaire known as the state-trait anxiety inventory.
After a night of no sleep, brain scans showed a shutdown of the medial prefrontal cortex, which normally helps keep our anxiety in check, while the brain’s deeper emotional centers were overactive.
“Without sleep, it’s almost as if the brain is too heavy on the emotional accelerator pedal, without enough brake,” Walker said.
After a full night of sleep, during which participants’ brain waves were measured via electrodes placed on their heads, the results showed their anxiety levels declined significantly, especially for those who experienced more slow-wave NREM sleep.