I've usually slept better on boats than on land. Do you fall asleep as a passenger in a car? On a train? Then you're probably a good candidate on a boat, whether mono (my experience) or multi-hull. If you find the cabin too confining, then if weather permits, sleep out on deck.
If you have any particular sleep problems, as discussed intelligently above, that's beyond my knowledge. But you may find that sleeping on a boat is easier and more restful than on land.