I would not offer 24 hour care, simply for the above reasons. Between the different families, you could easily end up working virtually non-stop. If you do want to offer something unique, then evening or overnight care only would likely make sense if there is demand for it in your area. Check into your local regulations as well, since providing care outside of "normal" hours may mean different rules/guidelines. And before you do it, think EVERY possible scenario through. What will you do if a child is wakeful, or sick, etc? Will you provide food? Supper and breakfast? And so on....