A study named “Overanxious and Underslept” done at UC Berkeley and published last month in the journal Nature Human Behaviour found that deep sleep, also known as non-rapid eye movement (NREM) slow wave sleep, calms and resets the anxious brain. This study provides one of the strongest neural links between sleep and anxiety to date - that insufficient sleep amplifies levels of anxiety (up to a 30% rise), and conversely, that deep sleep helps reduce such stress.
A series of experiments were done scanning the brains of 18 young adults, as they watched emotionally stirring videos after a full night sleep, and again after a sleepless night. After a full night sleep anxiety levels declined significantly, especially for those with the most NREM sleep. A night of no sleep however resulted in overactive emotional centers in the brain and also a shutdown of the medial prefrontal cortex (the part of our brain which keeps our anxiety in check). The researchers were able to replicate the results with another group of 30 subjects, and then also did an online survey with another 280 people of all ages. The amount and quality of sleep that participants got each night predicted how anxious they would feel the next day.
People with anxiety disorders routinely report having disturbed sleep, but rarely is sleep improvement considered a clinical recommendation for lowering anxiety. Now we know that there is a causal connection between sleep and anxiety and that specifically deep NREM sleep is needed to mitigate the anxious brain. Historically, people throughout industrialized countries sleep less, and at the same time report a marked increase in anxiety disorders. To quote Macbeth, sleep is the “balm of hurt minds”.
Eti Ben Simon, Aubrey Rossi, Allison G. Harvey, Matthew P. Walker. Overanxious and Underslept. Nature Human Behaviour, 2019