Hi,
I'm on ET also. I wondered about the same thing, and I've tried my hours several different ways over the past 3.5 years. But unless you're offering services that must be done in real time (like answering customer calls, for example), differences in hours don't have to be problems at all.
The spread varies, but ever since I first had two clients at once, there's never been a time when all were in the same area.
Right now, three of my clients are in ET, one in CT, and one in PT.
But two years ago, believe it or not, I had one ET, one CT, one PT, one New Zealander, and one Australian. Did I stay up all night to do work for the Eastern Hemisphere folks? No way. They woke up in the morning and found work done that I'd started on when they went to bed. Actually, it can be a very nice way to work for everyone involved.
I know it sounds risky and maybe even selfish. But this has absolutely been the best solution for me: Pick the hours that work best for YOU (and that you work the best in), then pick the clients who are fine with those hours. It doesn't limit your client choices nearly as much as you think it will.