Second deployment in Afghanistan, I took more of an administrative role since I was armorer for the company and took the night 12 hour shift in the TOC (Tactical Operations Command) for our company. Relatively easy and boring, but I did have my times where I busted my ass controlling communications for our unit throughout the area.
After I got off at 8 AM, I would go to the gym and workout. Followed by trying to get some sleep. Except our tent always got hot and when the AC shut off during the summer, it was 100 degrees easily. Toss in situations where people would constantly be in and out of the tent talking and opening the door to let the Afghan sun in, I just couldn't sleep. I was on my 3x the normal limit of sleep medicine, which caused me to be drowsy the next shift.
Knowing that all you need is some good rest and sleep, but you wouldn't get it for months, is miserable.