>>11331623
Dry prostate orgasms have greater fatigue than ejaculatory ones due to more intense and prolonged pelvic muscle contractions, higher activation of the parasympathetic nervous system, and a higher flooding of hormonal response.

Ejaculatory orgasms trigger a sharp dopamine spike followed by a prolactin surge that helps "close" the arousal cycle, however dry orgasms have sustained prolactin release, less dopamine, and higher oxytocin and endorphin levels—creating deep relaxation but also post-orgasmic tiredness.

Also the central nervous system may be more heavily engaged during prostate stimulation, leading to a form of sensory or neural overload that contributes to physical and mental fatigue afterward.

All that combined also makes me a lot more tired than jerking off. It's why a quick series of anal orgasms before bed helps me sleep so much better than a pre-sleep wank.