How can sleep deprivation prevent memories of a traumatic event?

In a study published in the journal Biological Psychiatry, researchers from the National Institute of Mental Health in Tokyo were interested in the relationship between sleep deprivation and fear associated with post traumatic stress disorder (PTSD).

In this experiment, researchers had two groups of healthy volunteers. Everyone watched a film with traumatic content and then one group was able to go to sleep, while the other was forced to stay awake for 24 hours (total sleep deprivation). Amazingly the group that had to stay awake had less measured fear of the film content than the group that got to sleep. The researchers hypothesized that a case of sleep deprivation, like acute insomnia after a life threatening trauma, may help people not form the fearful memories of the traumatic event.