@LukeAlmighty uhhh 4 hours for sure. especially if you can time waking up with your sleep cycle. there is an app on android called Sleep As Android that's really good at tracking that and waking you up at an appropriate time.

there are sleep schedules that focus on getting two 4 hour sleeps instead of one 8 hour sleep. or three 3 hour sleeps. there is some evidence to show that, at least as an adult, it might be healthier to do that, but i'm sure it just depends on the person. sleep seems to be something that everyone needs a different amount of and at different times.