I'm nocturnal by nature, so I've learned to get by on minimal sleep - usually 4-5 hours on work nights, and 7-8 on my days off. Thankfully I have a job that doesn't require early hours (typical shift is 12:30-8pm or 11am-6:30pm), or I'd be getting no sleep at all!
(I did adjust slightly when I had a 9-6 job, usually going to bed around 2-2:30am and waking up around 8)