Why Zebras Don’t Get Ulcers Part 3: Stress and Sex

Meenal Solanki
4 min readMay 25, 2021


I remember the giggles in our classrooms when it was finally that time of the year when the class reached the chapter on Reproduction in Biology. Kid you not, even aspiring medical students could not keep a straight face in that class. However, the effect of stress on sex and reproduction is not funny.

The Men

I think we all have some idea that the hormone testosterone plays some part in reproduction (don’t ask me, I don’t know, don’t care; but some of you may be interested, Google please). ‘Injury, illness, starvation, surgery, all bring down testosterone. Psychological stressors are just as disruptive.’ Fun fact shared by Dr Sapolsky in the book, lower the dominance rank of a social primate and down goes his testosterone level. Put a person through a stressful learning task and the same occurs. Remember glucocorticoids from Part 2, they block testes from producing testosterone. And there’s no prudent way to bring this up now, but you need to understand the mechanism behind your erections to understand how stress may be making you flaccid.

So here it goes. In order for a male to have an erection, he has to divert a considerable amount of blood flow to his penis. At this time obviously we don’t want the blood to rush to our muscles to fight or flee, which it does when we are under stress; refer Part 1. We want ourselves to be relaxed, our PNS to be activated, not the SNS (also refer to Part 2 in case you want to know more about these acronyms, else, key here is one has to not be stressed to have erections). But the author is smarter than us all and predicts your obvious question. If you’re having a good time while in the act, your breathing and heart rate will increase. Obviously this will kick in the sympathetic nervous system (SNS), which we all know from Part 2 is responsible for the stress response. Well that is why finally the ejaculation occurs. All this is complex and crazy, but true. The author also gives you a trick here my friend, which I doubt anyone of you will implement. In case you don’t want to ejaculate, suddenly start deep-breathing, this will relax you and kick in the parasympathetic nervous system (PNS) and maybe you won’t ejaculate…

So back to how being stress makes you flaccid -

  1. If you’re chronically stressed, blood vessels are clogged, blood flow will have issues (part 2 is literally about all this)
  2. If you’re stressed just before/during the act, blood moves towards muscles (fight or flight) and away from the penis
  3. If you are having a good time and then suddenly get stressed about something, you switch from PNS to SNS far faster than regular, et voila, premature ejaculation

Do you want to know whether your erectile dysfunction is psychogenic rather than organic impotency? The book has a method, but it involves putting electrode around your penis while you sleep, strongly recommend you to Not Try That at Home.

The Women

Again, to understand how stress may be making you infertile, you first need to understand your body. 2 main processes result in pregnancy — ovulation i.e. production of egg and the thickening of your uterine walls with blood to support the fertilised egg. But what happens with stress is again going back to our hormone glucocorticoids (refer part 2). They will inhibit your Follicle Stimulating Hormones (FSH) & oestrogen, making it less likely for ovulation to occur. They will also inhibit progesterone, disrupting the maturation of uterine walls. Release of prolactin during stress also interferes with the activity of progesterone. Those of you who are on birth control pills may be familiar with some of these terms, others please forgive me for this jargon.

Another fun fact the author shares is that oestrogen protects against osteoporosis and thus stress-induced decline in oestrogen can have bad effects on your bone strength. So no matter how much Calcium Sandoz or Horlicks Women you take, if you’re taking equal or more dose of stress, you are going to have bone strength issues.

What about your libido? Well there seems to be a strong link between presence of oestrogen in your body and your sexual drive. (This is established through experiments done on various animals, can refer the book for details.) And as we have seen above, stress is inhibiting oestrogen release, causing diminished libido.

A note on miscarriages. ‘The delivery of blood to the foetus is sensitive to the blood flow in mothers, decrease in uterine blood flow will cause disruption in foetal blood supply.’ Why will blood flow to the uterus decrease? You guessed it -

  1. Blood vessels are clogged, blood flow will have issues (part 2 is literally about all this)
  2. Blood moves towards muscles (fight or flight) and away from the uterus

Reduced blood flow means lesser oxygen and nutrition for the foetus. If this goes on for long, you know what can happen.

Now don’t be stressed about stress. Be with your loved ones, meditate, breathe, indulge in some self-care. Will probably elaborate on these in a subsequent article.