Conscious experience is probably the most familiar mental process that we know, yet its workings remain mysterious. Consciousness is not directly accessible for study. Hence the neurochemistry of consciousness is studied by examining the neurochemical correlates of well recognised natural states and alterations of consciousness. These include natural functions such as sleep and dreaming, attention, memory, etc. Altered states constitutes changes induced by drugs and by pathological states such as dementia, psychotic states etc.

In the present context neuro chemical process of consciousness will be explained by examining the neurotransmitters involved in waking state through various stages of sleep.