Most people know it as the major male sex hormone, but testosterone plays important roles throughout the body, including maintaining muscle mass and bone health, and supporting sperm production. In women, testosterone has a smaller but still critical role for libido, energy and mood.
Consistently low testosterone caused by certain health conditions and even medications can suggest something may be amiss, and some men do benefit from hormone therapy. But focusing on testosterone as a way to gauge combat readiness or optimize physical performance “is really misplaced,” said Shalender Bhasin, an endocrinologist and professor of medicine at Harvard Medical School. Your overall well-being and how you feel are more important, he added.
One of the issues with fixating on testosterone is that levels are constantly in flux, Bhasin said. The hormone is released in bursts and naturally rises and falls throughout the day, as well as over time. “If you draw the blood sample at the peak of the pulse, the level is going to be higher,” he explained. “So a single testosterone level can be highly misleading.”
And a number of factors can influence those fluctuating levels, including sleep, diet and stress. Here are 11 things that experts say can alter your level over time and on a daily basis.
Your age
Over time, the testes produce less testosterone, leading to gradually lower levels. “It goes down in all men as they get older, especially after 40,” said Jim Hotaling, a urologist, professor of surgery (urology) and director of the Men’s Health Program at University of Utah Health. This decrease may be about 1 to 2 percent each year, studies have found.
But while an age-related decline does exist, “in the vast majority of men, testosterone levels will remain within the normal range for most of their lives,” Bhasin said. Your overall health plays a role, too, he added. For example, men who gain more weight with age or develop chronic health conditions may experience a steeper rate of testosterone decline.
Your sleep schedule
Testosterone levels increase during sleep, and some research suggests that getting less sleep can impact the hormone. “If you don’t sleep well, that can cause low testosterone,” Hotaling said.
In one 2015 study, researchers tracked testosterone levels in 10 healthy men who underwent sleep restriction for a week. This resulted in lower testosterone levels during the day compared to the levels after the men had slept well the night before.
Another study found that those with shift work sleep disorder, which can affect people with nontraditional work hours, had lower testosterone levels than the workers without the condition.
The relationship between testosterone and sleep isn’t always clear-cut. Some research, for example, suggests the association varies depending on age as well as sex, but sleep is “really important” for overall health, said Bhasin.
“Sleep disturbances contribute to decline in reproductive function in general,” he said, including an increased risk of low testosterone and erectile dysfunction.
The time of day
Testosterone levels peak in the morning “and fluctuate second to second,” explained Hotaling, as the hormone is continuously released.
Some research has found it follows a wavelike pattern throughout the day, peaking between 6 and 7 a.m., then declining to its lowest point around 8 p.m. For this reason, blood samples to check testosterone levels are generally taken between 7 and 10 a.m.
The season
Time of year may also impact testosterone levels, possibly driven by factors such as daylight and temperature. Though there’s conflicting research on exactly when a seasonal peak occurs, testosterone levels may be higher in the summertime, said Justin Houman, a urologist, male reproductive medicine and surgery specialist, and assistant professor in the Department of Urology at Cedars-Sinai Medical Center.
With more sun, men are probably exercising more than in the winter, when “there’s a little bit of a dulling effect,” Houman said.
If you’ve recently become a parent
Fatherhood changes the brain and body in some surprising ways, and fathers may experience decreased testosterone levels when a child is born.
In a 2011 study, men who had a partner and became fathers had salivary testosterone levels that were 26 percent lower in the mornings and 34 percent lower in the evenings compared to the single men who weren’t fathers. More recent research observed that these levels may rebound by the time children are around 9 to 10 months old.
Some experts have suggested that this testosterone shift could be an evolutionary response to encourage caregiving. But testosterone changes around the time a baby is born “could also be multifactorial,” Hotaling noted. During this period, “men aren’t sleeping as well, and there are a number of things there, like more stress.”
If you’re exercising too intensely
Testosterone levels temporarily increase after exercise, though research suggests that older men benefit from less of a boost. Getting enough physical activity in general is important and can support levels within a healthy range. Resistance training, moderate-intensity aerobic exercise and high-intensity interval training may be especially beneficial.
But regularly pushing yourself to physical extremes — which might be the case if you’re participating in combat training or are an endurance athlete, for example — could have the opposite effect. Research has found that testosterone levels are sharply reduced after intense combat training.
With too much exercise, “your body gets worn down and goes into this kind of fight-or-flight mode,” Hotaling said.
Your diet
When supporting normal testosterone levels, “I think there is very little evidence that hyper-focusing on this diet or that diet makes a whole lot of difference,” noted Bhasin. But emphasizing a diet that contains plenty of whole foods, fruits and vegetables, lean protein sources and whole grains will benefit your overall health, in turn supporting your testosterone levels, he said.
Eating to maintain a healthy weight is particularly important because research has linked weight gain to a drop in testosterone levels, while weight loss may support a rise.
If you’re drinking too much alcohol
“If you’re having less than four or five drinks a week, that’s probably not having a significant impact,” said Hotaling, but heavier drinking may affect testosterone, research suggests. A 2024 meta-analysis found that men who regularly consumed alcohol had lower total testosterone than those who did not drink, possibly because alcohol may affect the hypothalamus-pituitary-gonadal axis, an endocrine system responsible for regulating reproductive hormones.
Alcohol contributes to other sexual and reproductive health challenges, such as erectile dysfunction or lower sperm count.
Your stress levels
It’s normal to feel stressed out from time to time, but regularly experiencing high stress can create a low-grade inflammatory response that alters your immune system, causes symptoms like headaches and exacerbates high blood pressure, among other side effects. Taking steps to minimize stress can also help since “stress is a big component of lowering your testosterone level,” Houman said.
Both types of stress, chronic stress (which is long-lasting) and acute (the short-term kind), can negatively impact testosterone and sexual function, a 2026 review article found. Chronic stress may have additional detrimental impacts, the authors noted, such as lower sperm count and erectile dysfunction, possibly because of how it causes sustained endocrine dysregulation and testosterone suppression.
Your current medications
Certain types of medications also “clearly suppress testosterone levels,” said Bhasin, such as opioids, glucocorticoids to reduce inflammation, anabolic steroids and some drugs that treat prostate cancer.
Chronic opioid use, in particular, “has emerged as a really important cause of severe testosterone deficiency,” noted Bhasin. In a large 2016 study of patients in the Veterans Affairs system that Bhasin co-authored, “we found that 20 percent of people who were getting testosterone treatment for hypogonadism were opioid users,” he said.
Whether your favorite team won or lost
Though “there isn’t a strong basis” for it, said Bhasin, some limited research has looked at how testosterone might be influenced by the concept of “basking in reflected glory.” Researchers in an older article looked at two small studies that observed how sports fans experienced their favored teams winning or losing. In both of these studies, the participants whose teams won experienced increased mean testosterone levels, according to saliva samples, and decreased levels when their favored teams lost.
If you think you might have low testosterone, your doctor can check your levels to see if treatment is appropriate for you. But Bhasin stressed that most men have normal levels, even as they age — and focusing on optimizing your health by getting enough sleep, exercising and eating well is often all you need to keep things within a healthy range.