I have been thinking about this for awhile and now have a pretty good idea of what I want to do. This has been one aspect of Skyrim that I would like to see be updated. The idea is to work on further integrating the need for you to drink eat and sleep adding a survival aspect to Skyrim hopefully without simply adding a layer of tedium but rather making food and cooking a much more interesting part of the game. Here is a simple breakdown on what I plan to do.

You have 3 categories

• Magicka <---> Thirst (0-100%) Drink beer ale wine to recover your thirst value. Not all bottles of wine you find are full. You must search for the higher quality drinks
  
• Health <---> Hunger (0-100%) Only prepared foods found in the cooking list restore hunger. You cant live off of cheese wheels and carrots.
  
• Stamina <---> Sleep (0-100%) Sleeping in your house allows you to fully recover your sleep value. Going to an inn will be very helpful and sleeping in the wild will net you meager results.

Its not all about filling some bars up. You have to think about what you drink and eat and where you sleep.

• Drinking <---> Sometimes makes you tired and hungry. ( Skooma will reduce hunger and sleepiness while making you more thirsty )
  
• Eating <---> Will always make you more thirsty and depending on the size of the meal will also tend to make you more tired.
  
• Sleeping <---> Sleeping makes you both thirsty and hungry ( Naturally because you slowly increase thirst and hunger over time ) ( Fast travel will tend to make you tired hungry and sleepy all at once... )

Side effects for thirst hunger and being tired.
By default Auto-regen is the only thing that will be effected.
In other words if I am at 50% hunger then my heal rate auto-regen shuts off at 60% of my health bar. I can still use a potion to fill up the rest and nothing else is effected. It works the same way for all 3 categories.

all 3 categories equally effect the overall speed of your auto-regen in each category.
This leaves a great deal of incentive to get rest as a pure magic caster because it would have a significant effect on the speed of your magicka regen. A warrior who does not use magic will want to drink because it will have an impact on how quickly his/her health and stamina regen as well. That should be enough incentive to keep all 3 bars as full as possible.

Note: I offset the percentage by 10% for all 3 categories. So the lowest your auto-regen can kick in at your most thirsty hungry and tired state is 10%. This also means that between 90-100% you will still refill your bars up to full. Only after it dips below 90% thirst hunger and sleep will you begin to see your auto-regen effected.

Other notes:
I will need to hand touch quite a few objects to add additional effects to them. It will only be for prepared meals and the various drinks already in the game. I may include additional cooking recipes depending on how things feel once in the game. This mod will have an important effect on all items from gear potions and food that give you bonus auto-regen. For some reason right now if you shut off auto-regen it makes it so all of those items are also negated. At 50% thirst even if I have a full suit of gear with magicka regen enchants I will still only auto-regen up to 60% magicka. a rough estimate on how long it will take to reach the 10% mark for all 3 categories if untouched is 2 in game days.

At last a primary needs mod!

But a note: With this system, if i understood correctly, my warrior for example will never have to drink anything since i never use any magicka. Likewise my mage will never have to sleep since he doesn't use any stamina (only perhaps for sprinting.) Imo make all 3 affect all 3 regenerations or find a way for a character to have the need to do everything.
Also, if possible, you could add carrying capacity and movement speed for lower percentages.

I was considering the idea of making it so your resistances were tied into this somehow. But yeah that is a good point to consider.

Ok I think I have an idea to make it so everyone needs to drink eat and sleep equally.

I will update the OP in a bit.
all 3 categories equally effect the overall speed of your auto-regen in each category. This leaves a great deal of incentive to get rest as a pure magic caster because it would have a significant effect on the speed of your magicka regen. A warrior who does not use magic will want to drink because it will have an impact on how quickly his/her health and stamina regen as well. That should be enough incentive to keep all 3 bars as full as possible. Ill post back with more details as they come up.

Question for anyone that might be able to help me. I am a bit concerned about this.
I am able to fully shut off magicka regen using this...
player.setav magickarate 0.0

but for some reason I am unable to fully turn off health regen even if I type this
player.setav healrate 0.0

I realize that modav is the better command because it is permanent but It disturbs me that I cant seem to shut health regen off using this...