Most people who take Ambien feel sedated and fall asleep, as expected, but rarely, some people show the opposite effect and become aroused or are unable to fall asleep. Experts aren’t sure exactly why this happens, but some research has suggested that because Ambien affects the inhibitory neurotransmitter, GABA and inhibitory neurons, this allows excitatory neurons responsible for transmitting activity to re-awaken and become active again because the inhibitory neurons are “asleep”.