Researchers at Harvard Medical School and Massachusetts General Hospital have found that when you don’t get enough sleep, your brain can’t get rid of stressful memories, leading to anxiety or post-traumatic stress disorder (PTSD).
Sleep is known to be critical to the consolidation of our memories, and sleep deprivation impairs memory and learning. The study involved 150 healthy adults. They all had to spend a number of nights in the sleep lab. A third of the participants received normal sleep, another third received restricted sleep (the subjects slept only the first half of the night), and finally, a third did not sleep at all at night and suffered the most from lack of sleep the next morning.
The following day, all project participants underwent a fear conditioning procedure using a three-phase experimental model to acquire and overcome fearful memories. At the same time, the subjects’ brains were observed using functional MRI.
It turned out that activity in the areas of the brain associated with the regulation of emotions (the prefrontal cortex) is observed only in people who have had enough sleep. For those who slept half the night, activity was greatest in areas of the brain associated with fear and least in areas of emotion control.
But in people who did not sleep at all, activity in areas of fear was quite low. And after 12 hours, their brain activity was more like the brain of a sleepy person. This suggests that the lack of a night’s sleep for the psyche is even worse than its complete absence. An analysis of the sleep of such people showed that sleeping for half the night leads to the loss of the rapid eye movement phase (REM phase) — this stage is important for memory consolidation.
Overall, the findings explain why partially sleep deprived people are particularly vulnerable to stress and prone to developing anxiety and PTSD.