So, what about the other 15%? One article recommends that for healthy adults, seven to nine hours of sleep is sufficient and goes on to explain that sleep deprivation can actually be considered a treatment for some folks with depression. It also goes on to explain that "death" can be a "side effect" from sleeping over nine hours per night (meaning, that people who sleep more than nine hours have a higher mortality rate -- they don't know why this is, either. Scary? You bet it is).
I personally need a lot of sleep. I find that I function better that way. I'm interested to find out how this is for other people. As far as sleep deprivation being a treatment for depression? Apparently, according to another article on WebMD.com, this was an old treatment that became outmoded by the use of antidepressant medication. In the most recent methods utilizing sleep deprivation, it is used in conjunction with antidepressant medication and may be helpful for patients considered to be treatment-resistant to normal methods. For the full text of the article, check out: WebMD sleep deprivation article. I'm going to take a nap.