A hood has a menacing air to it and in your dreams it may indicate that there is a part of you that feels threatened in some way.
More likely is the idea that part of your personality may be invisible to you and needs to be uncovered in order for you to function.
Traditional dream interpretation said that for a woman to be wearing a hood indicated she was being deceitful.
If a man is wearing a hood in your dream, it suggests that he is withdrawing from a situation.