Which inhibitory neurotransmitter promotes relaxation, sleep, and blocks intrusive thoughts?

GABA, or gamma-aminobutyric acid, is the main inhibitory neurotransmitter in the central nervous system. Its primary role is to decrease neuronal excitability throughout the nervous system. When GABA binds to its receptors, it leads to an influx of chloride ions into the neuron, making it more negatively charged and less likely to fire. This inhibition is crucial for promoting relaxation and sleep, as it helps counterbalance the excitatory signals in the brain that can lead to anxiety and intrusive thoughts.

Additionally, GABA's calming effects are particularly important in regulating mood and emotional responses, making it vital for preventing stress and facilitating restful sleep. The other neurotransmitters listed serve different functions: dopamine is associated with reward and pleasure, norepinephrine is linked to alertness and arousal, and acetylcholine plays a role in memory and muscle activation. Thus, GABA's specific role in inhibitory signaling is key to its effects on relaxation and sleep.