What causes tiredness and low energy after masturbating?

Tired afterwards: Partially psychic and partially autonomic.

Energy utilization: When you work yourself up during the event, you are calling extra energy factors into play.Stress hormones like adrenalin cause the heart to beat faster & and increase the tone of your blood vessels (blood pressure). In some ways it is like running a race. When ts over there is a reduction of the additional energy factors, so there is a physiologic let lown.