Rem-on neurons are located within the whereas rem-off neurons are located within the

REM sleep (Rapid eye movement sleep) refers to a specific phase of sleep in birds and mammalsm differentiated by brisk movement of the eyes, followed with slow muscle tone all through the body.

The control over REM sleep includes pathways of REM-on and REM-off neurons in the brain. The REM-on neurons are mainly cholinergic, that is, involve acetylcholine. The REM-off neurons stimulate noradrenaline and serotonin that among other activities suppress the REM-on neurons.

It has been suggested that the REM-on neurons basically activate REM-off neurons, thus, functioning as the mechanism for the cycling between non-REM and REM sleep.

The REM-on neurons are located inside the sublateral dorsal nucleus, while the REM-off neurons are located inside the ventrolateral periaquaductal grey.