Do Men’s Hormones Fluctuate Monthly?

Men’s hormones do fluctuate, but not in a tidy monthly cycle that mirrors a woman’s menstrual period. The dominant rhythm in male testosterone is daily, not monthly, with levels peaking in the early morning and dropping substantially by late afternoon. Some researchers have looked for longer cycles and found hints of seasonal shifts, but the evidence for a reliable 28-day hormonal pattern in men is thin and contested.

The Daily Swing Is the Main Event

If you want to understand how male hormones move, start with the clock on your wall, not the calendar. Testosterone follows a strong circadian rhythm, cresting in the early morning hours and declining through the day. In men aged 30 to 40, afternoon levels can run roughly 20 to 25 percent lower than morning levels.¹ A study comparing young and middle-aged men found even steeper swings, with total testosterone falling at least 43 percent from its morning peak to its evening low in all participants.² A densely sampled case study of a single man measured morning-to-evening testosterone drops of about 63 percent, alongside a roughly 92 percent decline in cortisol over the same window.³

These are not trivial blips. A man tested at 8 a.m. and again at 4 p.m. on the same day can produce results different enough to change a clinical diagnosis. This daily pattern is driven by pulses of luteinizing hormone from the pituitary gland, which in healthy adult men fire roughly every 55 minutes rather than shifting across a multi-week cycle the way they do in women.⁴ That rapid, steady pulsing is a core reason men lack the dramatic monthly arc that defines the female menstrual cycle.

What the Research Actually Shows About a Monthly Cycle

The idea that men have a roughly 28-day hormonal cycle surfaces periodically in popular media. The scientific support, though, is sparse. The most commonly cited study on the topic followed 27 men who collected daily saliva samples for 90 days. Researchers did find some nonrandom patterns that aligned with a 28-day interval, but only in a specific subgroup: partnered men who were actively trying to conceive. Unpaired men and men who did not want children with their current partner showed no such pattern. The authors themselves interpreted this not as an inherent male cycle, but as evidence that some men may adjust their testosterone responses in sync with a female partner’s menstrual cycle.⁵

A separate study tackled the question from another angle, measuring free testosterone across the calendar year in elderly community-dwelling men. The month-to-month variation they found was less than 15 percent, which the researchers described as marginal and insufficient to constitute a meaningful seasonal or monthly rhythm.⁶ Taken together, the existing data do not support the existence of a built-in monthly testosterone cycle in men.

Do Men Sync with a Partner’s Menstrual Cycle?

The “prospective fathers” finding above raises an obvious follow-up: does living with a woman cause a man’s testosterone to rise and fall with her cycle? A study designed specifically to test this hypothesis tracked testosterone in men whose female partners had regular menstrual cycles. The result was a flat line. Male testosterone showed no bump around the partner’s ovulation, and statistical analysis indicated the null finding was robust, not just a case of too few participants to detect a small effect.⁷ Whatever was happening in the “prospective fathers” study, it does not appear to be a general phenomenon where cohabiting men’s hormones lock onto their partner’s cycle.

The distinction matters because the claim “men have hormonal cycles too” often gets interpreted as “men basically have periods.” That framing overstates the evidence considerably. Women’s menstrual cycles involve coordinated swings in estrogen, progesterone, luteinizing hormone, and follicle-stimulating hormone across a roughly four-week arc, with predictable phases that repeat. Nothing comparable has been documented in men.

Seasonal Variation Is Real but Modest

If men lack a monthly cycle, do they at least have a yearly one? This is where the evidence gets genuinely messy. A large cohort study of men in Italy found that total testosterone peaked from August through October and bottomed out in March, with the difference between peak and trough reaching statistical significance.⁸ A study of salivary testosterone in both men and women found a similar fall-peak and summer-trough pattern.⁹

But other researchers have looked and found nothing. An analysis of testosterone data from two large institutional databases, one in Pittsburgh and one in Miami, found no statistically significant seasonal variation in either location, even when the data were broken down by age group.¹⁰ This conflict might partly reflect geography, differences in sunlight exposure, or methodological choices. One proposed mechanism involves the vitamin D receptor, which has been shown in mouse cells to promote testosterone synthesis by enhancing the activity of an enzyme involved in steroid production.¹¹ If sunlight-driven vitamin D levels matter for testosterone production, you would expect seasonal patterns to vary by latitude, which could explain why a study in sunny Miami might find nothing while one in northern Italy sees a clear seasonal wave.

Even where seasonal effects are detected, the absolute differences are small enough that most men would never notice them. We are talking about fluctuations measured in a few percentage points, not the kind of dramatic shifts that alter mood or energy in an obvious way.

What Actually Moves Testosterone Around

If men’s testosterone is not riding a monthly wave, what does cause it to shift beyond the daily rhythm? The short answer: a lot of things, but most of them are behavioral and environmental rather than calendar-driven.

Sleep is one of the better-studied influences. A meta-analysis of studies on sleep deprivation and testosterone found that total sleep deprivation (staying awake all night) produced a meaningful drop in testosterone, while partial sleep deprivation (getting fewer hours than normal for a night or two) did not reach significance.¹² This makes sense given that much of the day’s testosterone production happens during sleep. Chronic sleep restriction over weeks or months is a different question, and less cleanly studied, but the direction of the evidence points the same way: poor sleep means lower testosterone.

Cortisol, the body’s primary stress hormone, tracks closely with testosterone across the day. In a large study spanning adolescents to older adults, the typical within-person correlation between the two hormones was strongly positive, meaning they rose and fell together over the course of a day. About 28 percent of individuals showed a negative partial correlation, meaning that for some people stress hormones and testosterone move in opposite directions once you account for shared daily rhythms.¹³ Acute psychological stress, intense exercise, significant weight changes, and alcohol use all feed into this system, producing real-time shifts in hormone levels that have nothing to do with a monthly calendar.

The Gradual Decline with Age

The longest-running pattern in male hormones is not a cycle at all but a slow downward trend. Testosterone declines progressively with age, a shift that begins somewhere around the late twenties or early thirties and continues for the rest of a man’s life. Longitudinal data from the New Mexico Aging Process Study confirmed this trajectory, finding that over a span of roughly 14 years, both luteinizing hormone and follicle-stimulating hormone increased significantly in older men, while testosterone drifted downward.¹⁴

This gradual decline also blunts the daily rhythm. In younger men, morning-to-afternoon testosterone swings can be dramatic. By age 70, the daily variation shrinks to about a 10 percent difference, down from 20 to 25 percent in a 30-year-old.¹ The flattening happens because baseline levels are already lower, so there is less room for the morning spike to stand out. For clinical purposes, this has a practical implication: guidelines suggest that men over 45 can have their testosterone tested at any time before 2 p.m. and still get a reliable reading, while younger men should stick to early-morning blood draws.¹⁵

When Timing Matters for a Blood Test

The daily swing in testosterone creates a real-world trap for men getting tested. If you are 35 and your doctor orders a testosterone panel in the late afternoon, the result could land below the lab’s reference range even though your morning level is perfectly normal. In one study, 17 men who recorded at least one low reading (below 300 ng/dL) when tested after noon turned out to have completely normal levels at all three morning visits.¹ A single afternoon test could lead to an unnecessary diagnosis of low testosterone and a conversation about replacement therapy that never needed to happen.

If you are over 45, the stakes are lower because your daily rhythm is flatter, but an early draw is still preferable when possible. Either way, a single measurement on a single day is a snapshot that captures circadian position, how you slept the night before, whether you exercised that morning, and random day-to-day noise. Most clinical guidelines recommend confirming a low result with a second morning test before making any treatment decisions.

Irritable Male Syndrome and the Mood Question

Part of the appeal of the “male hormonal cycle” idea is that it would neatly explain why men sometimes go through moody or low-energy stretches. The concept of an “irritable male syndrome” was originally described in Soay rams, a seasonally breeding sheep whose testosterone drops sharply at the end of mating season, triggering nervousness, irritability, and lethargy. The term was later applied to human men experiencing similar symptoms during testosterone withdrawal.¹⁶

In humans, the relationship between testosterone and mood is real but less straightforward than the sheep model suggests. A review of the available literature found that both high and low testosterone levels were associated with increased rates of depression or mood disturbance, but there was not enough evidence to conclude that low testosterone routinely causes major depressive disorder in men.¹⁷ Men who experience clinically low testosterone, whether from medical conditions, aging, or medication side effects, do sometimes report irritability, fatigue, and depressed mood. But attributing a bad week to a hormonal “cycle” overstates what the biology is doing. Those bad weeks are more likely explained by sleep quality, stress, relationship dynamics, or ordinary variation in daily life than by a nonexistent monthly hormone wave.

Why the Myth Persists

The idea of a male monthly cycle has intuitive appeal because people experience their own moods as somewhat cyclical. You might notice that you have a few high-energy days followed by a slump, and the pattern seems to repeat on a vaguely monthly schedule. But human memory is prone to pattern-matching, and subjective mood logs do not always survive rigorous analysis. When researchers have tried to pin down a hormonal basis for these perceived cycles, the month-to-month variation they find in testosterone tends to be small, inconsistent across individuals, and dwarfed by the daily rhythm and the effects of lifestyle factors.

There is also a cultural motive at play. Framing men’s emotional variability as hormonal can serve as a counterpoint to the long-standing trivialization of women’s moods as “just hormones.” The impulse is understandable, but the biology does not actually support symmetry here. Women’s hormonal cycles are real, well-characterized, and clinically significant. Men’s hormonal fluctuations are also real, but they operate on different timescales (daily and lifetime) and through different mechanisms (pulsatile rather than cyclical). Equating the two creates a false equivalence that does not help either group.

Testosterone Is Not the Only Male Hormone That Moves

Discussions about male hormonal fluctuation tend to fixate on testosterone, but cortisol and estradiol also shift meaningfully across the day. In the densely sampled case study mentioned earlier, estradiol, the primary form of estrogen, dropped about 39 percent from morning to evening.³ Men produce estradiol through the conversion of testosterone, so the two hormones track each other to some degree. Cortisol’s daily swing is the steepest of all, dropping over 90 percent from morning to night in that same study.

Follicle-stimulating hormone (FSH) follows a different trajectory. Rather than cycling daily, it tends to creep upward over years. In the New Mexico Aging Process Study, 43 percent of subjects had elevated FSH at some point during follow-up, a much higher proportion than the 10 percent who showed elevated luteinizing hormone.¹⁴ Rising FSH in older men reflects declining feedback from the testes and is one of the markers clinicians use when evaluating age-related reproductive changes. None of these hormones, though, shows a reliable monthly oscillation in men.

How Women’s Seasonal Testosterone Patterns Compare

One genuinely surprising finding from the seasonal-variation research is that normally cycling women show larger relative swings in testosterone across the year than men do. In a study measuring salivary testosterone, women’s fall peak was more than double their summer trough, a relative change far larger than anything seen in male participants.⁹ Women using hormonal contraceptives had both lower baseline testosterone and a flatter seasonal profile, suggesting that the seasonal signal is tied to endogenous ovarian activity rather than external factors like sunlight alone.

This finding complicates the popular narrative that testosterone is a stable, always-on hormone in everyone except menstruating women. In reality, testosterone fluctuates in both sexes, just through different patterns and on different scales. Men’s dominant rhythm is daily. Women’s includes both a monthly menstrual-cycle component and, apparently, a seasonal one. The hormone itself does not care about gender categories; the control systems layered on top of it differ.

1
PubMed Central. The effect of diurnal variation on clinical measurement of serum testosterone and other sex hormone levels in men
2
PubMed. Diurnal rhythms of serum total, free and bioavailable testosterone and of SHBG in middle-aged men compared with those in young men
3
PubMed Central. Diurnal Fluctuations in Steroid Hormones Tied to Variation in Intrinsic Functional Connectivity in a Densely Sampled Male
4
Reproductive Medicine International. Different of Hypothalamic-Pituitary-Gonadal Axis in Male and Female
5
PubMed. Monthly patterns of testosterone and behavior in prospective fathers
6
PubMed. No major month to month variation in free testosterone levels in aging males. Minor impact on the biological diagnosis of ‘andropause’
7
PubMed Central. The female menstrual cycle does not influence testosterone concentrations in male partners
8
PubMed Central. Seasonal Variation of Testosterone Levels in A Large Cohort of Men
9
PubMed Central. Seasonal variation of salivary testosterone in men, normally cycling women, and women using hormonal contraceptives
10
PubMed Central. Seasonal Variation in Serum Testosterone Levels: Evidence from 2 Large Institutional Databases
11
PubMed. VDR promotes testosterone synthesis in mouse Leydig cells via regulation of cholesterol side chain cleavage cytochrome P450 (Cyp11a1) expression
12
Sleep Medicine. Effect of partial and total sleep deprivation on serum testosterone in healthy males: a systematic review and meta-analysis
13
PubMed Central. Diurnal Coupling between Testosterone and Cortisol from Adolescence to Older Adulthood
14
PubMed. Longitudinal changes in testosterone, luteinizing hormone, and follicle-stimulating hormone in healthy older men
15
PubMed Central. PURLS: It’s time to reconsider early-morning testosterone tests
16
PubMed. The irritable male syndrome
17
PubMed. The effect of testosterone levels on mood in men: a review