This study explored how cortisol, a stress hormone produced by the adrenal glands, affects male sexual function, specifically penile erection. Although cortisol has long been suspected to influence arousal and erectile function, very few in vivo studies have examined its actual role in humans.

What the researchers did:

• They studied 54 healthy adult men exposed to erotic stimuli to trigger different stages of sexual arousal.
• Blood samples were taken from both the cubital vein (systemic circulation) and the corpus cavernosum (erectile tissue) during various stages: flaccid, aroused, rigid, and detumescence (return to flaccid).
• They also tested the effects of cortisol (as prednisolone), norepinephrine, and endothelin-1 on penile tissue in the lab.

Key findings:

• Cortisol levels dropped significantly in both systemic and penile blood as arousal increased.
• During detumescence, cortisol stayed the same in the bloodstream but continued to drop in penile tissue.
• There was no significant difference between cortisol levels in the bloodstream vs. the penis at any stage.
• In lab tests, norepinephrine and endothelin-1 caused strong contractions of erectile tissue, but prednisolone (cortisol analog) had little to no effect.

Conclusion:

Cortisol appears to play an inhibitory (suppressing) role in male sexual arousal — likely acting on the brain or central nervous system rather than directly on erectile tissue. These findings suggest that high cortisol (like during stress) may interfere with sexual performance. Future research could explore if men with erectile dysfunction show different cortisol patterns during arousal compared to healthy men.

You can view the study here.