This month’s myth is entitled, men don’t have hormonal cycles. Now, I think everybody out there is aware that women have menstrual cycles – at least, the vast majority of them do – occurring on close to a monthly basis. Obviously there is some variation, but basically it’s what we call a monthly cycle even though it’s not necessarily a month. Now, these hormonal rhythms are sometimes, in some women, accompanied by emotional cycles and physical changes that our cultures LOVES to make jokes about, and have even used, unfortunately, as a rationale on occasion for limiting women’s access to power, leadership, and even some professions. Like a jet plane fighter or something like that. The assumption that goes along with this misunderstanding is that men experience no such cyclic biological mood or behavioral kinds of patterns. It’s generally believed that, or at least there’s an understanding, without any questioning, that men live in a kind of steady state of hormonal calm, and therefore they’re not at the mercy of fluctuating sex hormones like their female compatriots.

Nothing could be further from the truth.

This month’s myth-busting session will focusing on presenting you with the scientific data on sexual hormone cycles in human males, and if there’s evidence – maybe there is, and maybe there isn’t – that these cycles may have behavioral or mood consequences that are related to them. Now, there is much data that suggests that human males have both daily hormone cycles and perhaps yearly hormone cycles. Daily cycles are called circadian cycles – circa, meaning around, and the dia part meaning day, and annual rhythms are called circannual rhythms, and there are other kinds of names for them, but basically they mean around the day and around the year. Numerous have identified a daily rhythm in testosterone production. Now, testosterone is what people call the "male" hormone. It’s the main androgen that’s made, and that fuels male sexual function and libido in males. By the way, it also is the libido or desire hormone for females as well. We’ll probably get to talk about that at some other point in our myth-busting sessions. It is also criticially involved in gestation; that is, in fetal development, in the development of male sexual organs and the male brain. Males and females don’t have exactly the same brain – they start out with the same brain, but when these male hormones wash over it it changes it a little bit. And it’s also the same hormone that takes the basis for our genitals and turns them into male genitals; that is, penis and scrotum, rather than becoming a clitoris and labia. But that’s another story.

Again, although females do have some testosterone, the "male hormone," males produce much higher levels throughout their lives and it’s primarily produced in their testicles (or testes, or balls, or whatever you prefer to use). The daily cycle of testosterone production is quite large – that is, the cycle of it – with an overall change from high to low of approximately 43% over the day. The highest levels are produced in the morning, beginning around midnight, and they start to fall around noon. The lowest levels are found in the evening. Testosterone production appears to be related primarily to the individual man’s sleep cycle, and then secondarily to the light/dark cycle of the year. There does appear to be a yearly cycle as well. The Northern Hemisphere is somewhat different from the Southern Hemisphere – that is, Western Europe, the United States, Russia and China would be the Northern Hemisphere. It’s somewhat different in the Southern Hemisphere – Australia, Africa, and South America. It seems to be higher in summer and fall, and lower in winter and early spring. And there are concomitant – that is, related – changes in sperm production and so forth, that are related to that.

Now, do these daily or yearly hormone variations affect men’s behavior, as supposedly the monthly hormone changes that sometimes supposedly accompany the menstrual cycle of women have been accused of doing? Well, let’s see. What do we know about sex differences in the variability in mood, emotion, and behavior. Do we know anything about that? And in fact, we know a lot about that. Several research groups over the past 3 decades have conducted studies specifically to evaluate whether it’s true or not about this assumption that women are more emotionally variable and unpredictable than men. Is it true that women are supposedly these emotional animals, and you just can’t predict what they’re going to do. There’s a thousand jokes about it – every comic has some joke about it, and our culture tends to believe that, that women aren’t predictable, and somehow it’s related to their menstrual cycle.

All of these studies have concluded that there are no differences in the day to day mood changes between men and women, that men are no more or less unpredictable in their moods, emotions, or behavior than are women. Put another way, when comparing men and women, studies found that both men and women were subject to similar changes in mood and behavior patterns over time. So – it’s just not true that women are more changeable than men. There may be some women who are affected by their menstrual cycle, but there are also men that are affected by cyclical changes in their life. And here’s an interesting study that I found that was done in Japan by a large company that operated buses and taxis, and they had a very large number of drivers. And they did this study not for any scientific purposes, but because they were concerned about very high losses that had resulting from accidents, and they couldn’t figure out what to do to lower this accident rate which was costing the company a great deal of money. So each man who was working for the company was evaluated on a day to day basis to determine whether there were any patterns in his mood and efficiency. And they did it over a month – they used the month as the basis for it. And did it on an individual basis, because obviously they couldn’t look for when they bled every month, because men don’t do that. There wasn’t such an obvious thing. And after they developed this information on each individual man, they used the information they collected to make schedules for each man as to when he should be off and on, and when he should drive and not drive. And the schedule of each man was adjusted to take into account the best working times for the drivers, based upon what had been learned from these individual mood and efficiency cycles which they found in the individual men. And the result was that the accident rate dropped 33%. So clearly, the individual men were having mood cycles and efficiency cycles, but they were individual – you couldn’t see them from the outside. There wasn’t a signal or sign from the outside. So men have cycles too – they are just not as obvious as women’s monthly menstrual cycles, because men don’t have obvious signs, like bleeding or swelling, or something that tells us where they are.

So I want to end this myth by telling you a story. When I was asked by someone in the media about the suggestion that women really shouldn’t be trusted to take on international leadership positions because of their biological and therefore psychological cycles, and lack of predictability, I responded by saying that men cycle every day. So perhaps because their testosterone is very high in the morning, and many people assume – and by the way there is research data to support that testosterone is related to aggressive behavior – we should only permit our male leaders to declare war and to negotiate peace treaties in the evening, when their testosterone is at its lowest, and perhaps only in winter, when it’s the lowest season for testosterone. Now, does that really make sense to you? Maybe it does make sense, I don’t know. But anyway, I think we have to pick our leaders, pick our jet fighters, pick our people by their individual characteristics, their individual health, the individual calm, and not by some belief that we have about their sex in general. And so, hormones are hormones, and both men and women cycle on a daily basis, on a monthly basis, on an individual basis, perhaps on a yearly basis, but that doesn’t tell us too much about who they are and how they behave. And that’s our myth-busting session for this month.