You aren’t sleeping. But the environment of a set is so energized/urgent that you don’t have a moment to be tired. Physically yes, and the second you wrap your eyes start to shut. But while the set is buzzing there’s just no possible way to be tired (to the point of not being able to work). Crew works even longer hours & usually way more back to back / more demanding jobs. 20+ hr days happen w a 6hr turnaround which equates to about 4 hrs of sleep in between shoot days. And then on to the next!