after doing that myself, a few times, it's funky, and frankly, it starts to get really hard to do @_@
apparently, after the 3rd day, doctors can declare you clinically insane, but yeah, nothing THAT bad, except the possability of slipping into a coma once u do sleep, and for thoes of you with shit endurance, yeah, dying
i myself, start to mildly halucinate after 5 days (conversations, object placements, inability to tell whats real, and whats fake mostly.), and i have an increasingly harder time differentiating between them and reality as time goes on.
only managed 7.5 tops myself, i chose to end it. frankly, i don't think i'd like to try doing that again, it is rather scary after 6-7 days of not knowing whats real, and whats your brain going AWOL.