It is involved in most behaviors, including anxiety states. This inhibitory neurotransmitter reduces the brain's electrical activity. The brain needs its electrical activity, of course, but too much can produce many problems. Among the various problems related to GABA deficits are anxiety and epilepsy. Without enough GABA, brain cells fire more than they should and keep the brain charged up.
Noradrenaline tends to be associated with more pleasant kinds of arousal.
Adrenaline can also be pleasant, but too much is likely to produce anxiety and jittery feelings. Adrenaline also helps you breathe more easily, fighting symptoms of asthma and allergies. In the movie Pulp Fiction , a character whose heart has stopped gets a jump start from a shot of adrenaline directly into the heart. Having too little, you're likely to feel underaroused, unmotivated, or sleepy, and will be susceptible to headaches. Caffeine speeds up the release of both, especially adrenaline .