Non-rapid eye movement sleep determines resilience to social stress

Resilience, the ability to overcome stressful conditions, is found in most
mammals and varies significantly among individuals. A lack of resilience
can lead to the development of neuropsychiatric and sleep disorders, often
within the same individual. Despite extensive research into the brain
mechanisms causing maladaptive behavioral-responses to stress, it is not
clear why some individuals exhibit resilience.  To examine if
sleep has a determinative role in maladaptive behavioral-response to
social stress, we investigated individual variations in resilience using a
social-defeat model for male mice. Our results reveal a direct, causal
relationship between sleep amount and resilience—demonstrating that sleep
increases after social-defeat stress only occur in resilient mice.
Further, we found that within the prefrontal cortex, a regulator of
maladaptive responses to stress, pre-existing differences in sleep
regulation predict resilience. Overall, these results demonstrate that
increased NREM sleep, mediated cortically, is an active response to
social-defeat stress that is both necessary and sufficient for promoting
resilience. They also show that differences in resilience are strongly
correlated with inter-individual variability in sleep regulation.