Just got back into the gym yesterday after a few days off, poked myself in the eye with a spruce branch on Tuesday, got an abrasion on my cornea. It's healing well but what a miserable injury.
Did upper body. Since shoulder surgery I've been doing most exercises one-armed, and increased the strength in my good arm by 10-20%. The recovering shoulder is up to around 50% of the weight I used to lift pre-surgery. The goal is to be able to do 10-12 pullups.
I also have trouble sleeping if I work out late. It's not adrenalin, but it's something. Maybe endorphins? I'd say, if you feel good during the day what's the issue? Maybe you're one of those lucky people who doesn't need much sleep, and it just takes a good amount of exercise to bring that out. If not, it'll catch up and you'll find yourself napping during the weekend.
