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Why Men Fall Asleep After Sex

To the dismay of many women, it is a fact of life that a large percentage of men fall asleep after achieving an orgasm. As this occurrence is the subject of debate as to the lack of sensitivity and attentiveness of men, we have included it in the Love Relationship Stress Section so as to acknowledge its existence as a relationship issue experienced by many couples. In this article, we will explore the hormonal basis for this pattern in men’s behavior.

Biological Changes

For sexual intercourse to successfully take place, a series of cardiovascular, neural, and metabolic changes must take place within a man, including increased heart rate, increased systemic blood pressure, erection of the penis (which is dependent on penile pressure), and elevated blood pressure at the abdominal aorta and heart rate during sexual intercourse.

Exertion Level

Of all intercourse positions, the man-on-top position requires the highest exertion. As a wide variation of exertion exists for different men, it prevents labeling the general estimate of sexual activity being the equivalent of climbing two flights of stairs. (At the peak of orgasm, mean maximal heart rate is estimated at 114 beats per minute and maximal blood pressure at 163/81 mmHg. – considered a high blood pressure level).

Sexual Arousal Involves These Neuropeptides

• Oxytocin injected into the cerebrospinal fluid causes spontaneous erections in rats, reflecting actions in the hypothalamus and spinal cord.

• A study of men found an increase in plasma oxytocin immediately after orgasm.

• Vasopressin (dopamine) is secreted during sexual arousal, followed by a selective release of oxytocin at the time of ejaculation.

• Orgasm increases blood pressure, heart rate, plasma catecholamines (dopamine, epinephrine, norepinephrine ) and prolactin.

• Prolactin has many effects including regulating orgasms. Prolactin provides the body with sexual gratification after sexual acts, counteracting the effect of dopamine, which is responsible for sexual arousal.

• The amount of prolactin can be an indicator for the amount of sexual satisfaction and relaxation (providing a sedative effect).

• Prolactin plasma levels increase during orgasm and remain elevated 30 min after orgasm. In contrast, none of the other endocrine variables were significantly affected by sexual arousal and orgasm.

• Unusually high amounts of prolactin (caused by emotional stress) are suspected to be responsible for impotence and loss of libido.

• Research data confirms that prolactin is continually secreted after orgasm and, (as compared with oxytocin), seems to represent a more reliable and sustained marker for orgasm in men.

• These findings further reinforce the role of prolactin as a feedback mechanism for moderating dopamine release and quieting sexual drive.

So the real culprit in these neuropeptides is prolactin. Acknowledging that high levels of this substance leads to impotence and lack of libido, it is easy to understand why the combination of exertion, followed by the secretion of prolactin acts to create a sedative effect.

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Sources: Wikipedia (http://en.wikipedia.org) Changes in Oxytocin and Vasopressin Secretion During Sexual Activity in Men Journal of Clinical Endocrinology and Metabolism 65:738–741 Specificity of the Neuroendocrine Response to Orgasm During Sexual Arousal in Men Journal of Endocrinology 177:57–64 Cardiovascular and Endocrine Changes During Sexual Arousal and Orgasm Psychosomatic Medicine 61:290-291 (1999) Heart Rate, Rate-Pressure Product, and Oxygen Uptake During Four Sexual Activities Archives of Internal Medicine 1984 Sep;144(9):1745-8

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