Dreaming of being in bed may be an indication of a lucid dream event. This means that you are aware of being asleep in a dream state. Somehow, your mind is accepting the limitations of your sleeping condition. However, the bed can also be a place of laziness, sickness, death, or sexual encounter. If the bed feels like a symbol for any of these metaphors, the dream may be saying something about how you perceive yourself.
Freud would be inclined to see the bed as a womb, as well. Indeed, the covers pulled over the head on a chilly morning can make the bed a utopian haven against a difficult world.