Napping on kayak.

Just be mindful to stay extremely well hydrated prior to taking a nap. It will help with sea sickness, as well as long exposure to the sun. Rig up a canopy of sorts and keep yourself lathered in sunscreen. Other than that, if you're secured to a nice piece of kelp, with enough slack to prevent a swell from rolling you over, nap away. I do it =/

I don't think I even need to state the obvious, make sure you're wearing a pfd and tether yourself to your boat.... you know, just incase.