I feel that this may take its toll on me. Some days I'm sprinting hard and getting a lot of work done, and I'm exhausted by 4-4:30pm. But I can't leave early be

I feel that this may take its toll on me. Some days I'm sprinting hard and getting a lot of work done, and I'm exhausted by 4-4:30pm. But I can't leave early because its against norms. This builds resentment in me because the work is getting done, but I have to sit around and burn time for superficial appearances.