

When people have tried this they found you can’t just stay awake. Your brain ends up turning bits of itself off at a time, so while you can talk and move around you’re basically not fully conscious and will mix up words or not be able to move at the same time. They called it “microsleep”, and it’s the main reason why nobody tries to go for longer without sleep any more: beyond a certain point you’re not really awake or asleep.
This is what my old housemate did, starting in the 90s. Worked out quite well for him. My dad used went round the world with the navy in the 50s and used to talk about how some other cultures did stuff like this.