Your brain can take a hell of a lot of abuse until it can’t.
I was holding it together for nearly 3 decades before it was unable to keep up with major sleep deprivation anymore. 10-12 hours of sleep a night and a nap midday couldn’t keep me going.
I was blacking out time while driving, had barely any memory, had involuntary muscle spasms and couldn’t physically recover from injury in a reasonable time.
Once I started on CPAP I recovered by leaps and bounds, I sleep way less but am fully present in the world, like being on high dose of caffeine without taking anything.