Let’s highball the number of hours slept and lowball the episode duration and say someone sleep an average of 4 hours a day for 3 months. What effect does that have on them? It seems like it would take someone apart. Even 1 month on 5 hours of sleeps seems like it would wear them down. Is that the case?
It seems like the military would have been interested in learning how people with mania or hypomania can stay functional for weeks or months on little sleep, even if it wears them down over time, given that military service can do far more than wear people down.
The military does study this, and will provide amphetamines where it seems useful such as in combat conditions or for pilots on long flights. I don’t think they are as interested in keeping people in a state of such little sleep for such long periods as much as they would be interested in avoiding that situation.
They have to be aware that it will happen, though, and want to prepare for it. For example, special forces soldiers may very well have missions where keeping the mission as short and safe as possible involves not taking sleeping breaks in the middle of it. Thus, it would be advantageous to them to learn that, if only because they wouldn’t then need to resort to potentially addictive and stress-inducing substances like amphetamines.
Don’t a lot of the harder military training regimens involve learning how to function well even under little sleep? The Marines’ Crucible, Ranger School, SEAL training, all involve going for several days on little or no sleep. Some of that is testing people to see how they deal with adversity but it’s also to see if they can maintain high performance on little sleep over several days.