I've been sieving through CK to see how the well rested ability is used. From what I've gathered its a spell, no surprise there. What I haven't worked out is how it actually is implemented. There is a quest called "Player Sleep Quest" which as it says checks for when the player sleeps but is of little use information wise. The bed in Breezehome has no scripts attached to it so I drew a blank there. In essence I want to create a new ability that is applied when player sleeps on a specific bed. Creating the ability is not a problem, how I get it "into" the player is, do I use OnSleep? The Wiki is useless about describing OnSleep, I hope you guys can throw more light on this, thanks.

Well rested is linked to owned furniture/location, and the location having playerhome keyword or locreftype, cant remember which.

You could look at using registerforsleep like you suggested, applied to a player alias in a quest.