How many hours of sleep does a person really need to function properly?

I would say at least 6 or 7 hours.

Depends on who it is. I can function during a nine-hour shift on less than an hour of sleep.

I would say at least 6-8, I need 8-10 to function good throughout the day. I love sleep, and I need it. It depends on the person though, if a person is used to not sleeping much then they are fine without it.

Yeah, 6-8 sounds good, but there are exceptions of course. I like to sleep, and I do it often. Not always at the right time though. ^_^

You'd be amazed at what the human body is capable of. In Army Ranger School a person is required to take part in intense physical activity and training exercises for extended periods of time while under major sleep deprivation. Special ops is not for everyone however; it takes a different kind of person who is willing to push past all kinds of emotional and physical pain in order to grasp the full potential of an endurance few people realize exists.

I would say six to eight hours.