A Quartz news report discusses several research studies that explore brain activity during REM sleep.

A new study published in Science Advances studied the physiology and functionality of REM sleep in a group of rats and provides insight into the cortical activity and the sub-cortical pathways that result in this activity. The level of detail of this study provides a major step forward for our understanding of the effect that REM sleep has on our brain and cognitive behavior.

The authors studied groups of rats who were allowed to sleep, but prevented from entering REM sleep for three days. Six hours before assessment, half of the rats were allowed to sleep normally, and half continued to be deprived of REM sleep. The rats that were permitted to sleep normally then demonstrated raised levels of REM sleep within those six hours. This enabled a comparison of the effect of recent REM sleep between groups. An additional control group of rats were allowed to sleep normally throughout the study.