A report in 1966 by a Dr. Frederick Snyder claimed that REM sleep had a “sentinel” function that helps animals get into fight or flight mode when attacked. Dr. WANG Liping and his team at the Shenzhen Institute of Advanced Technology have proven this hypothesis.
The team found a common circuit that regulates innate fear and REM sleep. They published their findings in Neuron on January 21st.
When exposed to trimethylthiazoline (TMT), an odor that indicates the presence of a predator, animals in REM sleep roused quickly. Animals that were not in REM sleep, however, were not as quick to respond.
The area of the brain, the medial subthalamic nucleus, contains a high density of corticotropin-releasing hormone neurons. These neurons produce a lower arousal threshold during REM for detecting predator threats and an increased defensive response after awakening.
For further information on this study, read their report here.