I kind of felt like you don't need to sleep very much on hardcoe mode. I poked around in the GECK to see if I could find any leads on editing this, but I'm no modder, so I didn't have much luck. I imagine changing the rate at which the meter increases might be kind of hard, but simply decreasing the max value of the meter might be easier... Pure speculation, though.
Know if it's possible?
The rate the meter increases is a single game setting for each of the three needs (dehydration, sleep deprivation, starvation). It's pretty easy to change, but you need to make it fit with your TimeScale settings or else the game'll feel odd.
I'm currently using a TimeScale setting of 12 (1 real-life minute to 12 game-minutes or 2 real-life hours to 1 game-day) and deprivation/starvation/dehydration settings of 30/25/18 respectively (that means every 30 real-life seconds your sleep deprivation need goes up by 1, every 25 seconds your starvation need goes up by 1, etc). It basically works out that you've got to sleep once every 20 hours, got to eat once every 16 hours, and have to drink every 12 hours or you get a penalty. (EDIT: Note that none of these things are part of the mod download - they're part of some personal tweaks I've done, and have no real interaction with this mod)
If I were to go in and redo the needs entirely, I'd rejigger the stages so you don't always get hit with sleep deprivation (or starvation/dehydration) penalties at 200, then more at 400, even more at 600, etc until you die at 1000. Instead, I'd make it so you can survive indefinitely without sleep, you're just going to have extreme penalties to stats, while it'll take about a week or so to die of starvation or three days to die of dehydration. You can change all that stuff pretty easily in the GECK (the new Gameplay->Dehydration (or Hunger/Sleep Deprivation) dialogue is pretty intuitive from what I've seen so far, so once someone gets around to doing this it shouldn't be too difficult.
But all of that's outside the scope of this mod, really, and should be in a dedicated hardcoe Needs Mod (or module for this one, if I ever get around to making it).