During REM sleep, which of the following physiological events occurs?
- A Core body temperature regulation remains intact
- B Penile/clitoral tumescence is absent
- C Atonia of skeletal muscles due to active inhibition by glycinergic/GABAergic neurons ✓
- D Heart rate and respiration become slower and more regular compared to NREM
Correct answer: C. Atonia of skeletal muscles due to active inhibition by glycinergic/GABAergic neurons
Explanation
REM sleep is characterized by muscle atonia caused by active inhibition from pontine reticular formation neurons via glycinergic and GABAergic pathways that hyperpolarize spinal motor neurons. This prevents acting out of dreams. Temperature regulation is abandoned in REM (poikilothermy-like state). REM is accompanied by irregular heart rate and respiration, and penile/clitoral tumescence is a normal feature — its absence suggests organic erectile dysfunction.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.