Nearly half of men over age 45 have low testosterone levels, a condition that can leave them feeling weak, depressed, and not at all interested in intimacy. Over time, low testosterone can even make bones brittle and prone to breaking. Low testosterone, or “low-T,” as many pharmaceutical ads call it, can make a man miserable. 
You’re probably aware of a few conditions that contribute to low testosterone levels. The usual suspects include high cholesterol, high blood pressure, diabetes, and addictions to certain substances. If you don’t suffer from one of those common culprits, you might assume you’re not at risk. 
But not so fast: As researchers trace the causes of low testosterone back to a menagerie of discrete sources, it starts to seem like there’s a threat to a man’s hormonal balance hiding around every corner. Here are some of the most surprising (and dismaying) things that have been associated with low testosterone levels:
1. Certain Cholesterol-Lowering Medications
High cholesterol can totally mess with testosterone levels. We know this. Unfortunately, a common treatment for high cholesterol might also cause low-T. 
“The problem is that we have become accustomed to expressing the effects of our therapies in terms of the average changes in groups as opposed to also considering the range of changes in individuals,” the authors wrote. “We need to acknowledge this shortcoming if we are going to learn more about benefits and risks of drugs and really understand whether side effects … truly matter.” 
In other words, we don’t know if the testosterone-lowering effects of statins are significant enough to worry about just yet. We only know that they exist.
2. Being in a Happy Relationship
When it comes to low testosterone, it seems you just can’t win for losing. Lots of men worry about their hormone levels because they want to have happy, fulfilling romantic relationships, and low-T can get in the way of physical intimacy. 
So here’s a fine how-do-ya-do: Having a happy, fulfilling relationship can actually correlate to lower levels of testosterone in men. A 2003 study from the journal Hormones and Behavior asked 122 men to describe their romantic relationships. Then the researchers collected saliva samples that were used to test participants’ testosterone levels. 
It turns out that the men who reported being in “committed romantic relationships” had testosterone levels that were, on average, 21 percent (!) lower than those of their swinging bachelor counterparts. Maybe this can help explain the arcane process by which “Netflix and chill” slowly becomes actually—you know—watching TV or snoozing on the couch together.
3. Getting Old
Some drop in testosterone is unavoidable. It’s just part of the adventure called aging—that fun journey during which your body falls apart, bit by bit, hurtling down the ceaseless and inevitable path toward its final rest in peace. 
You can’t stop this one, we’re afraid. The good news is that the testosterone decrease associated with aging does tend to even out if you live long enough. According to the American Urological Association, approximately 40 percent of men age 45 and older have clinically low testosterone. That number drops to just 20 percent who are age 60 and older, then settles down at around 30 percent for men over 70. That’s small consolation, but you gotta take what you can get.
4. Struggling With Obesity
Every day, health reporters introduce us to a truckload of horrors associated with obesity. Here’s your daily dose. 
A 2010 study found that a full 40 percent of obese, nondiabetic participants—all male, aged 45 or older—had low testosterone. Throw diabetes into the mix and that figure leaps to 50 percent. If that’s not enough to convince you obesity is bad for your hormones, check out the authors’ conclusion on their findings: “In view of its high prevalence, obesity is probably the condition most frequently associated with subnormal free testosterone concentrations in males.” In other words, when it comes to low-T, obesity is the No. 1 culprit.
5. Joining the Army
If a spaceship full of benevolent aliens landed on your lawn and hollered, “Quick! Where can we find the highest concentration of testosterone around here? We need to extract it in a harmless, noninvasive way or else our whole planet will explode and all your pets will die!” you might point them to the nearest U.S. Army training camp. 
All those sweating, screaming, straining young recruits are bound to be packed to the brim with testosterone, right? Um…somehow, no. A 1990 study looked at what happens to testosterone levels when men go to boot camp. It wasn’t really an Army boot camp that the researchers studied, but a “90-day shock incarceration program, modeled after military boot camp,” which we consider close enough. 
Anyway, those guys didn’t get more manly as they ran obstacle courses and saluted and got yelled at, or whatever happens at boot camp. Instead, they developed lower testosterone levels during their 90-day incarceration. “There were significant differences among individuals in both mean scores and changes over time,” researchers found. 
The implications of this research are pretty fascinating. These findings dovetail with previous studies that suggest testosterone production slows down when men feel like their social status has dropped. How’s that for some fragile masculinity?
6. Health Food
Flaxseeds are really good for you. They’re full of omega-3 fatty acids and every type of fiber you could want moving through you. They also have an insanely high concentration of chemicals called lignans. For the most part, lignans have a great reputation. Most notably, they might guard against prostate cancer and polycystic ovary syndrome (PCOS). 
Here’s the thing about both of those conditions, though: They’re associated with high testosterone levels. In one study, researchers had a woman with PCOS take 30 grams of flaxseed every day for around 100 days. At the end of the study, the woman’s total serum testosterone had decreased by 70 percent. That’s terrific news for women with PCOS. It’s not great news for men who are worried about low-T. But before you throw out your flaxseed waffles, you should probably talk to your doctor. 
Low testosterone isn’t something you can self-diagnose, and the health benefits of flaxseeds might actually make any hormonal effects totally worth continuing to include them in your diet. Like anything health-related, you should only make these decisions after a nice, honest conversation with a for-real medical professional.
7. Burning the Midnight Oil
Who has time to sleep anymore? Not people with low testosterone, that’s for sure. A study out of the University of Chicago found that young men who averaged about five hours of sleep per night reduced their testosterone levels by 10 to 15 percent. And those guys were 24 years old and fit. 
How much damage do you think a sleepless night is doing to the testosterone levels of, say, a 35-year-old dude with prediabetes or a cholesterol problem? Takeaway: If you want to keep those hormones in balance, get your beauty sleep.
