Does The Blind From Birth Dream?

Does the blind from birth dream?If they do what do they actually see?If they don't,does it explain the concept of dream as sleep imagination based on memories of the dreamers past as well his future aspirations and fear?

When you are troubled,you have nightmares,but when you are happy and confident nightmares are at distance.And the same goes in real life,people are insecure and down trodden when they are ignorant of issues,but daring and agile when they know.what you don't have a clue about,you can't solve.