During ejaculation several chemicals are released. Oxytocin and vasopressin are linked to relaxation of the muscles, throughout the body, thus leading to decreased arterial blood pressure and subsequently, to decreased blood flow to the brain. Melatonin, which is responsible for the circadian rhythm, which tells us when to sleep and when to be awake, is also released.

Prolonged masturbation might give enough time for proper stimulation of all male reproductive organs, thus preparing them for the male orgasm. On the other hand, prolonged masturbation associated with increased physical activity might cause tiredness which is usually not felt until the ejaculation.