PHILADELPHIA, Pa. — Sleep is critical to our health and wellbeing, especially when it comes to repairing the brain. While studies have shown how damaging not getting sleep can be to the human body, a new report is revealing that only getting a partial night of rest may be even worse. Researchers say getting half a night’s sleep hijacks the brain and makes it difficult to process fear.
The study finds restricted sleep is common among medical workers and military personnel. Unfortunately, this leaves many of them unable to properly unlearn the trauma from fear-filled memories. The result can be a higher risk for mental health conditions like anxiety or posttraumatic stress disorder (PTSD).
“This study provides us with new insights into how sleep deprivation affects brain function to disrupt fear extinction,” says Cameron Carter, Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, in a media release.
Is no sleep really better than less sleep?
A team from the University of Pittsburgh and Harvard Medical School examined 150 healthy adults during a three-part sleep study. One third of the participants got a normal night’s sleep. One third experienced a restricted sleep where they only slept for the first half of the night. The final group did not get any sleep at all. Study authors then put all the volunteers through a fear conditioning program.
“Our team used a three-phase experimental model for the acquisition and overcoming of fearful memories while their brains were scanned using functional magnetic resonance imaging,” explains Dr. Edward Pace-Schott from Harvard Medical School and Massachusetts General Hospital.
Researchers showed the group three colors, with two of the options connected to a mild electrical shock. Once properly conditioned to fear certain outcomes, the group received fear extinction training, where one of the colors has its shock turned off and is now “safe.” Later that day, the group was tested to see how they now reacted to the three colors again. This measured their ability to recall fear and see how well their brains have unlearned the threat.
Dr. Pace-Schott and the team examined brain scans of these reactions. The results revealed people getting normal rest experienced brain activation in areas connected with emotional regulation. In people experiencing a lack of sleep however, the activity is much different.
“We found that among the three groups, those who had only gotten half a night’s sleep showed the most activity in brain regions associated with fear and the least activity in areas associated with control of emotion,” Pace-Schott reports.
Researchers add they were surprised to discover people getting no sleep at all lack brain activation in fear-related regions. When measuring fear extinction 12 hours later, their brains actually resembled the people getting normal rest.
Sleep restriction’s impact of rapid eye movement
The study theorizes that a lack of sleep cuts into the brain’s ability to reach rapid eye movement (REM) sleep. Researchers say this level of rest is important for memory consolidation and usually starts during the end of a normal night’s rest.
Dr. Carter says noninvasive brain imaging is pointing to a link between sleep deprivation and normal fear responses. The result may leave people lacking quality sleep vulnerable to PTSD.
“Medical workers and soldiers often have curtailed or interrupted sleep rather than missing an entire night’s sleep,” Dr. Pace-Schott concludes. “Our findings suggest that such partially sleep-deprived individuals might be especially vulnerable to fear-related conditions such as posttraumatic stress disorder.”
The study appears in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.