When your sleep rhythm is all fucked up and you "reboot" by staying up all night one night, and then going to bed the next night using the fatigue from not getting any sleep the night before. Use of a sleep aid is an option, of course, just to ensure that sleep can be reached. Usually an insomniac's desperate attempt (short of drinking until passed out or committing suicide) at getting some sleep.
Jon: Fuck, I'm tired. I'm doing a sleep reboot.
Mike: What's that?
Jon: I stayed up all night last night because my sleep pattern is all fucked up; so I'm going to bed tonight using the fatigue I have right now. Plus, I might take some Advil PM before I go to bed, too. This fucking sucks. FUCK INSOMNIA!