I've searched, and I can't find anything for this. Is there a mod in existence that requires a bed for the level-up process?

The way I would implement it would be, I would not prevent the player from leveling up (I don't believe I can), but what I would do is remove the player's available perk points to spend until they sleep in a bed. They would be available to spend for an in-game hour after sleeping, and then be removed again.

Should I move forward with this, or would this be a duplication of effort? Let me know. This would be a very easy mod to put together (like, an hour, tops), and would require SKSE.

The thread on http://www.gamesas.com/topic/1415232-relwiprealistic-room-rental/ got me thinking about this. Currently, other than the Well Rested bonus, most of the necessity of sleeping is not present in Skyrim like it is in Morrowind and Oblivion, and I'd like to bring that back again.

No one has made such a mod that I am aware of.

Is there any way to disable the level up menu until you sleep? (like when you are a werewolf, for example)

I wish, but I don't think that's exposed to Papyrus, via SKSE or otherwise, without disabling the entire menu system (inventory, magic, the whole 9). Removing available perks to spend was the only concession I could think of that would approach this functionality.

It would definitely stretch the dev time beyond the projected one hour, but what about:

Since in the current SKSE beta, you can invoke menus through scripting, when the PC has enough XP to level up, go to a state that disables the menus but also registers for key presses to invoke all the menus EXCEPT the level-up menu?

Eh. Some people actually still use the core select screen instead of the direct hotkeys. I'll look at the beta but if I can't just "grey out" the level-up menu, I won't be able to do what you're describing without breaking things I shouldn't be breaking.

And I thought an hour was generous, it's probably a 30 minute job. Here, I'll write the script for it right now so I can just go do it when I get home:

scriptname _REF_MainScript extends ReferenceAliasEvent OnInit()RegisterForSleep()endEventEvent OnSleepStop(bool abInterrupted)	if !abInterrupted		Game.SetPerkPoints(_REF_myPerkPoints.GetValueInt())		RegisterForSingleUpdateGameTime(1)	endifendEventEvent OnUpdateGameTime()	Game.SetPerkPoints(0)endEvent

And you'd also need a thing to actually retrieve their current perk points on some periodic basis, but, yea, that's the idea. Or maybe I'm oversimplifying this. I tend to round down my development times a lot ^^;

I guess if no one has done something like this I'll go ahead and do it. It won't hurt anything, at least.

This could easily be a feature of your Survivor Series Chesko.
Love this stuff!