It is well established and commonly understood that women have regular and predictable hormonal cycles that govern much of their biology and behavior but did you know that men’s hormones also cycle? Most specifically testosterone, the primary male hormone that makes men men, has two important cycles that govern much of their biology and behavior..

Daily Testosterone Fluctuations 

Testosterone has a diurnal rhythm (a daily/circadian cycle) marked by peak levels in the morning and a low at night. It looks like this:
 (Citation: Bremer, 1983)

This means men wake up with their highest daily testosterone levels circulating through their blood, which typically helps drive them to start the day strong from both an energy and libido perspective. Subsequently, they are typically most charged first thing in the morning and the first half of the day. As the day goes on testosterone declines steadily with the lowest levels appearing at night, ranging 25-50% lower than the morning peak*. This daily pattern often dictates much of how driven a man is as the day goes on and particularly at night.

Sleep then restores testosterone levels as the body rests, recovers and builds. After a good sleep, testosterone has built up over night and is again at peak levels the following morning, providing the energy and masculinity for the upcoming day. The crucial role that sufficient overnight rest plays means if men don’t sleep enough (or well enough) they can’t restore their testosterone and build up as high of a reserve and peak, leaving them starting off at a deficit. This is not a big deal after a night or two but it can have an understandably huge impact over time. One of the reasons men lose testosterone as they get older is due to chronic sleep deprivation. Many other factors contribute but sleep is the trump card that helps even the most stressed out, poorly fed and out of shape guy keep testosterone at respectable levels. This is also likely tied to why men can fall asleep just about any time and are so quick to fall asleep at night. If running low at the end of the day or perpetually depleted, sleep is one of the body’s main avenues for restoring the substance that fuels much of a man’s biology. The sleep-testosterone relationship is also why it’s important to limit exposure to bright lights at night. Bright light postpones/blocks/prevents the brain’s release of melatonin, a powerful hormone that signals the sleep sequence and subsequent testosterone production.

When testing for testosterone, it is important that daily rhythm is taken into account as morning samples will naturally measure higher than afternoon or evening samples and that a few days of sleep deprivation, if not the norm, could also dramatically alter test results. Ideally, any testing should be done under normal conditions and retesting should be done under similar conditions.

*Noticeable is the difference between young and old men on the testosterone daily rhythm. Although this is yet to be fully explained it is a widely observed difference and is often used to discern how “youthful” a man might still be. Men who feel substantially vital in the morning and considerably less so at night are representing a normal and youthful male hormonal pattern.

Yearly Testosterone Fluctuations 

While daily hormone rhythms are an important part of understanding male behavior and function on a day to day basis, an equally important cycle to be aware of is annual/yearly/seasonal testosterone changes. On an annual basis, testosterone reaches a peak in late fall and a low in spring. It looks like this: 

Citations: Seasonal Variation of Testosterone and Waist to Hip Ratio in Men: The Tromsø Study

The evidence for seasonal variations of testosterone in men

As you can see, testosterone is at its highest in the fall and lowest in the spring. This little talked about (and little known) picture of the male hormone is extremely relevant when looking at men’s health and behavior. This means, from a biological perspective, men are at their most manly in the fall and least manly in the spring. Although there is debate over why men have this seasonal pattern, this cycle can help explain much of male behavior from a bigger picture approach. Men can expect to have much more masculine energy, libido, drive and command during some of the year and much less during other parts of the year, for no reason other than seasonal variability of their primary masculinizing hormone. Subsequently, any hormone testing or evaluation needs to be done with this pattern as background. Getting tested for testosterone levels now (May) would likely show most of us lower than we actually are, giving a false low test result. Similarly, getting tested in October would be getting a measure of the highest levels we can produce (but only do for a month or two), giving a false high score. More troublesome is when a man gets tested during a high or low season and then retested 6 months later at the exact opposite of testosterone season and then it is concluded that something (often an intervention or drug) has had a positive or negative impact. All that was really learned is the man’s hormone range, not a hormone change.

Managing Male-ness

There are a thousand different opinions on how to manage hormones, testosterone in particular. The scope of this post isn’t concerned with increasing male hormones (although I think I will put together a little something on simple things we can do to help optimize testosterone). More generally the goal was to simply to bring awareness to these two important and often very helpful male cycles and leave you with a few things to keep in mind when analyzing how you (or the men in your life) feel and perform.

  • Testosterone peaks in the morning and lowers throughout the day, bottoming out at night. Don’t be surprised or discouraged if and when masculine energy is a bit low at night. *Women: this is thought of as the best time to ask for something. **Men: this is when to be very aware of what women are asking if you.
  • If a man doesn’t exhibit daily fluctuations it is a sign of a problem.
  • Sleep restores testosterone. Lack of sleep = lack of testosterone.
  • Testosterone is at its highest in the fall and lowest in the spring. Don’t be surprised or discouraged if there’s less drive, libido, energy and confidence in the half of the year with lower levels, particularly the spring months. *Women: Don’t be surprised if there’s a bit more attention paid to you in the fall and winter- this is why the busiest season for babies is July-Sept. Sperm count is reflective of testosterone levels.
  • If a man doesn’t experience seasonal variations in testosterone or masculinity it’s the sign of a problem.
  • Testosterone is a reflection of the health state of the body. Healthy men have healthy testosterone levels and cycles. Suboptimal levels and/or cycles is a reflection of poor health. 
  • Any testing should keep both daily and yearly rhythms in mind. This is a neglected component that can vastly alter how to interpret test results.

Men are biological creatures and we need to keep that in mind. So if you find yourself reading this article on a spring night it might not surprise you that you (or your man) are pretty tired and have been just a little off in general lately. That’s just part of being a man. But so is waking up full of macho bravado on a fall morning so keep that in mind come September.

Thanks for reading, have a great day!

P.S. These dates presented here are for males in the Northern Hemisphere as the seasons are opposite in the Southern Hemisphere.

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