Sleep deprivation continues to be a large problem in Western society and as senior author, Matthew Walker stated, “These findings are especially worrying considering that two-thirds of people in the developed nations fail to get sufficient sleep.”
About 18 young adults participated in the study. They viewed 70 facial expressions which revealed a variety of emotions (aggression, happiness etc.) The test was conducted twice – first after proper sleep and later after sleep deprivation. Brain scans and heart rates were taken from each participant.
The results from the fMRIs showed sleep-deprived brains cannot distinguish between friendly or threatening faces. Additionally, heart rates, too, did not respond normally to the different expressions.
Participants interpreted friendly or neutral faces as threatening while sleep-deprived. But when participants went through proper sleep and experienced REM sleep (or dream sleep) they could accurately identify the different facial expressions.
“The better the quality of dream sleep, the more accurate the brain and body was at differentiating between facial expressions,” said Walker. “Dream sleep appears to reset the magnetic north of our emotional compass. This study provides yet more proof of our essential need for sleep.”
The study was published in the Journal of Neuroscience.