Post-orgasm tiredness is common in men. Most men fell asleep after having sex. And there is a scientific reason for this.
According to health experts, the body chemistry of men changes just after he reaches orgasm. This happens when the biochemical prolactin is released, it makes him tired and he tends to sleep after an intimate session. Also, exertion and tiredness after sex tend to reduce energy-producing glycogen in muscles in men.
This usually doesn’t happen with women, even if they reach orgasm. Women stay semi-sexually aroused and they love to indulge after-play like post-sex cuddling, love and conversation. As women have less muscle mass, they don’t feel so lethargic after sex.
During sexual acts, the body releases oxytocin hormone. This makes you feel relaxed as it reduces anxiety and stressful thoughts. This also makes it easier for men to sleep afterwards.
Also, sex with lights off makes you feel more relaxed and stress-free. Darkness gives your body a signal that it is time to sleep and the hormone melatonin initiates your sleep cycle. This perfect trifecta of prolactin, oxytocin, and melatonin ignites snoozing time.
So as per scientists, there are many potential biochemical and evolutionary reasons for post-sex sleepiness. So it is not a negative sign of your relationship.