Does lack of sleep cause depression?

Yes, lack of sleep can cause depression, however that is not the only reason/cause of depression. Lack of sleep means lack of energy throughout the day. You do not feel active in anything that you do. There is dullness on your face and you are left with no enthusiasm. Lack of concentration/ focus also arises from the same. Since you get aware of these things that happen with you, there is a possibility of not only feel sad but this sadness can lead to depression as well.

Basically you body needs rest and time to recharge. It is healing process in a way. When you body doesn't get those 6-8 hours of sound sleep, naturally the entire day goes in laziness, dullness and no enthusiasm left. This becomes a routine and after a period of time. This causes you to feel sad, hopeless, worthless and helpless. But when you feel sad for long periods and the feelings become intense it leads to depression.

Hi

No doubt ,without sleep, u can't do any work properly, not having good concentration, whole day u'll feel very dull & less active, that means sleep is like taking rest for our whole body(brain function, nerve function, etc). Lack of sleep can causes depression .