After ejaculation, a refractory period usually occurs during which a man cannot achieve another orgasm. This can be anywhere from less than a minute to several hours, depending on age and other individual factors.
Most men experience a lag time between the ability to ejaculate consecutively, and this lag time varies among men. Only few guys are able to have consecutively acts. Age also affects the recovery time; younger men typically recover faster than older men. During this refractory period it is difficult or impossible to attain an erection, because the sympathetic nervous system counteracts the effects of the parasympathetic nervous system. It’s thought this just gets a genetic cause involving testosterone cycle too and there is no treatment useful to change situation.