If I'm really exhausted and feel like I'm gonna die but still have to work, I've found that a 15-minute nap is amazing for "taking the edge off" so I can become functional again. If I'm stressed enough I can even have some lucid dreaming happen, or awareness of my surroundings even tho I'm asleep (like sleep paralysis) which is almost as fun. Under normal circumstances, yeah it's hard to nap in under 20 minutes but I bet it'd become easier if I made it a habit.