Alberto Ramos, MD, FAAN, University of Miami, Miller School of Medicine, Miami, FL, discusses theories of REM sleep. The brain is very active during REM sleep – specifically, the cerebral cortex, which seems to be almost as active as if an individual were awake. The only way to differentiate between the cerebral cortex being in an awake versus REM state is by looking at muscle tone – whereby due to muscle atonia during REM, this value will be very low in comparison. Regarding theories of why REM sleep exists, Dr Ramos describes a view concerning neonates; REM sleep consists of about 50% of sleep for newborns – which is argued to be responsible for the development of an individual’s cortex. Another theory considers REM as a virtual reality platform, whereby through a term known as proto-consciousness, individuals learn to facilitate everyday behaviors and actions during REM. In a more pragmatic notion, REM sleep allows for the solidification of memories and the improvement or maintenance of emotional health; there are many instances where a lack of REM has been discussed in correlation with depression and poor mental health. Furthermore, Dr Ramos states that REM sleep may also help maintain core body temperatures, which is essential in sleep and vital core bodily functions. This interview took place at the American Academy of Neurology 2022 Congress in Seattle, WA.