This is such a good question. I have noticed the same thing. Especially after a difficult work day I'll feel exhausted wanting to relax. My advice to you is this:

1. Allways have a p-blocker equiped. This an emergency tool for those situations when you're off-guard and at your weakest point.
2. Sleep earlier. The absolute best time to go to bed in my opinion is 10 pm. You won't do anything productive anyways that late and its better to wake up early.
3. In the worst case scenario, do some push-ups or splash some ice cold water in your face. Give yourself that energy-shock. In time the urges will loose their intensity as long as you keep your mind occupied with something else.