A new study published in the journal Cell sheds light on the neural mechanisms associated with REM sleep and their connection to diseases such as Parkinson's.
The induction of rapid eye movement (REM) sleep, also called REM sleep, has not been well studied. Abnormalities in REM sleep, in which we dream, precede various diseases. In particular, REM sleep behavior disorder, in which patients physically act out dreams by moving and vocalizing during REM sleep, has been noted as an early symptom of neurodegenerative diseases such as Parkinson's disease.
The cause of these abnormalities was unknown. In this study, the researchers identified two types of neurons in the brainstem (pons and medulla oblongata) that trigger REM sleep. These neurons form circuits that connect to areas of the brain that control cortical activation, rapid eye movement, and loss of muscle tone—all of which are characteristic of REM sleep.
Artificial activation of this circuit induces REM sleep even in awake mice, in both light and dark phases. Moreover, inhibition of these REM-inducing cells in mice resulted in disturbances similar to those observed in patients with Parkinson's disease: body movements during REM sleep and a significant reduction in REM sleep.
Patients with Parkinson's disease and REM sleep behavior disorder had fewer REM sleep-inducing cells in the brainstem, providing clues to the cause of the disorder. These findings are expected to improve our understanding of the mechanisms and significance of REM sleep and help develop new methods for preventing and treating sleep disorders and related conditions.