Make your response by clicking on the letter you are choosing. There are several stages of sleep. Stage 3 has slow wave EEG and REM has alpha waves.
Sleep is a condition in which the mind is completely at rest and is shut off from the outside world.
Sleep is governed by circadian rhythms. Sleep walking is a common problem arising from acting out dreams. Psychoactive drugs work by altering the way brain chemistry controls neural communication in our brain. There are four general types of such drugs. One type is a 'depressant'.