11 things that can regularly change your testosterone levels

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 optimise physical performance “is really misplaced,” says Shalender Bhasin, an endocrinologist and professor of medicine at Harvard Medical School. Your overall wellbeing and how you feel are more important, he adds.

One of the issues with fixating on testosterone is that levels are constantly in flux, Bhasin says. 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 explains. “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.

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,” says 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 per cent 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 says. Your overall health plays a role, too, he adds. For example, men who gain more weight with age or develop chronic health conditions may experience a steeper rate of testosterone decline.

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 says.

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.