I work out in the morning, so it's not that I'm still aerobic from the exercise. I drag my ass through the day and stare at the ceiling at night. It's actually funny: I'm getting the reward of doing the exercise of increased energy, just at the worst possible time.
Maybe I'll go to two workouts a day. If this keeps up I'll exercise 24 hours a day and never sleep and get that circus-freak job I've always wanted.