Which neurotransmitter is increased during the awake state; decreased during stages 1, 2, and 3 non-REM sleep; and absent during REM sleep?

Which neurotransmitter is increased during the awake state; decreased during stages 1, 2, and 3 non-REM sleep; and absent during REM sleep?

• A. Serotonin
• B. Norepinephrine
• C. Glycine
• D. Acetylcholine

Answer: (D)

Norepinephrine. Awakefulness relies on the ascending arousal systems, including norepinephrine from the locus coeruleus, which is high to promote alertness. In non-REM sleep, activity in this system wanes, so NE release decreases. During REM sleep, the NE system is essentially silent, contributing to the dream state and reduced sensory arousal. Acetylcholine, on the other hand, is elevated during REM (and also active in wake), so it is not absent in REM. Glycine is primarily involved in spinal motor inhibition during REM, not a global wakefulness/arousal transmitter. Therefore, the pattern described fits norepinephrine.

Norepinephrine.

Awakefulness relies on the ascending arousal systems, including norepinephrine from the locus coeruleus, which is high to promote alertness. In non-REM sleep, activity in this system wanes, so NE release decreases. During REM sleep, the NE system is essentially silent, contributing to the dream state and reduced sensory arousal. Acetylcholine, on the other hand, is elevated during REM (and also active in wake), so it is not absent in REM. Glycine is primarily involved in spinal motor inhibition during REM, not a global wakefulness/arousal transmitter. Therefore, the pattern described fits norepinephrine.