What is the marite of dream?

Answer 1

I suppose your question is "What is the merit of dreaming?".

Dreaming helps to process what our minds have experienced during the day and to cope with stress. Dreams are often about things which are on our mind during the day which suggests the mind has trouble letting go of things which might cause stress to an individual. Dreaming about such significant issues might help us in coping with them better.

I think, though, that there is no 'purpose' in any biological sense of dreaming and that it is a by-product of the process that is falling asleep and waking up - which are the phases of sleep where dreams can occur in which the mind is somewhat active but less controlled by consciousness, making for unusual associations with whatever is fresh in the mind.