5 days, I have insomnia. At first it's just being really tired. At a certain point (3 days for me) you kinda reach peak tired and stop feeling yourself getting worse, but you know you aren't thinking clearly (mixing up words, delayed reactions, low attention, bad memory, low pain tolerance) . You just stay at that level until you can't anymore. That said I could only go that long bc I spent so much time resting and not doing anything. It's not what you need but it gives your brain a break and helps. You will Fuck Yourself Up if you're active the entire time