Why not harshly punish those who actually cause the accidents. You know being very tired can impair driving far more than alcohol...Should we police that also ? I say let the punishments begin when someone actually gets hurt. Being tired doesn't seem as deliberate as getting behind the wheel drunk and it could be hard to prove in court.
I do know of two different cases where people were killed by drivers that fell to sleep after staying up all night working so you may have a point. Maybe they should be penalized by not not as harsh as a DUI, mostly to deter other's from being irresponsible behind the wheel.
I just think the whole DUI system is too rigid and doesn't take the drivers particulars into account (Eg tolerance level).I still think DUI should be a crime though...mainly because EVERBODY knows the risks .