Hello! Why Ejaculation Causes Me Tiredness And Loss Of Energy

Hello!
Why Ejaculation causes me tiredness and loss of energy that I can't be comfortable all the day? I know people who don't have the same problem, also when I sleep everything goes good and I recover my energy back.. but the problem is I can't sleep as fast as I can after it.. so I suffer a lot from being in a state of weakness and I feel like my heart beats faster all the day.