Testicles: they don’t call them a man’s jewels for no reason. After all, they’re the source of all our manliness, producing testosterone daily, which gives us muscle definition, the hair on our faces, and the ability to perform sexually. This should explain, then, why we prize them so much, and why it hits so close to home when people like Tom Green and Lance Armstrong are diagnosed with testicular cancer — both of them got a testicle removed, and Green even had his operation televised.

There’s another condition that’s particularly scary for men: testicular atrophy, colloquially known as shrinking balls. Finding out your balls are shrinking is especially scary because you probably won’t feel anything resembling a tumor underneath, however, you’ll sure as hell be wondering what’s causing it and if you’re in danger of anything. If you ever find yourself going from walnuts to grapes down there, it could be because of one of these five reasons.

No Sleep for Shrinking Balls

In case you haven’t heard, sleep is extremely important to our overall health. Not only does it restore physical energy but it also restores our capacity for attention and memory, and boosts metabolism and heart health. Even better, it puts us in good moods.

Some research, however, suggests that losing sleep can shrink the balls. In a study from last year, researchers at the University of Southern Denmark surveyed nearly 1,000 young men about their sleep schedules, interruptions in sleep, and other habits. They also took blood samples and measured sperm counts, and found that men who had problems sleeping — insomnia, going to sleep late, or inconsistent sleep — had a 29 percent drop in sperm count. What’s more, their sperm were 1.6 percent more likely to be deformed, and their testicles had shrunk.

The researchers also noted that people who sleep late are more likely to lead unhealthier lifestyles, which could include smoking and drinking, but even then, it’s a good reason to get more sleep.

What’s That About Alcohol?

We all love our drinks in one way or another, whether they’re glammed up with fruity flavors or served neat. Alcohol has been found to benefit our health in many ways; red wine’s resveratrol is a relatively powerful antioxidant, and a drink or two can boost our creativity. But just like most things, drink too much, and you’re more likely to harm your body than help it.

Such is the case with alcohol and testicular size. In a study published this September, researchers found through both in vivo and in vitro studies on rats that alcohol caused changes to Leydig cell shape and function. These cells are located adjacent to the testicles’ seminiferous tubules, which are where sperm cells are produced. In turn, the tubules shrunk, and subsequent processes involving the way alcohol alters testicular energy metabolism and sperm cell mitochondria led to cell death. Together, these processes led to testicular shrinkage in the rats, and the researchers believe the same may be true for humans.

The good news, however, and it’s rather huge: All you have to do is quit drinking, and your testicles will likely bounce back to the size they were before.

Aluminum, Who Knew?

Okay so, most of us love to eat. And what keeps our food warm when we don’t have an actual heat source? That’s right, aluminum foil. Depending on the types of food you’re eating, the metal could be leaching in, and you’re eating it. But aluminum is found in other things too, such as tobacco, alcohol (here we go again), and even in the air.

Exposure to too much aluminum may cause a low sperm count and infertility, and a side effect of smaller testicles. In a study from last month, researchers examined 62 sperm samples and measured aluminum content, finding average of 339 parts per billion (high), with some men even having aluminum has high as 500 parts per billion. Those with the higher levels of aluminum were more likely to have low sperm counts and were therefore less fertile. Such exposure may lead to oxidative stress in the testicles, causing cells to die, and the testicles to shrink.

Limiting aluminum exposure by choosing chemical-free cleaning and personal care products may help, as well as using BPA-free plastic or glass bottles for drinking, rather than plain plastic.

Getting Kicked One Too Many Times, As If You Didn’t Suspect It Already

Our testicles have perhaps the most pain receptors concentrated in any one area of our bodies. We need them because they are the key to our reproductive success, even as they hang outside our bodies, vulnerable to attack. Getting kicked in the balls is enough to knock even the strongest man to his knees, as the pain receptors send signals through nerves that extend to the ears, stomach, and groin.

Thankfully, many men’s testicles don’t experience such trauma daily — except for those into skateboarding. For these certain groups, or those who experience one serious hit, the balls may indeed shrink. A study from 1999 (kind of outdated, yeah, but still relevant) found that 50 percent of men who experienced “blunt scrotal trauma” saw a reduction in the volume of the injured testicle.

Thankfully, getting hit in this area is relatively rare. But if you want to be extra safe, you can get yourself a cup.

Smoke Your Balls Away... with Marijuana?

Data has been conflicting for years on many of the long-term effects of marijuana. Studies have suggested that long-term use affects the brain’s reward system, causes brain damage, and lowers kids’ school grades. But for each study that finds a problem with it, there’s another one that puts the concern back at square one.

Testicular atrophy is one such issue, although many of the studies suggesting it does cause shrinkage are relatively outdated — from the 1980s. Nevertheless, the majority of it suggests that smoking weed lowers testosterone levels, either directly or through precursor hormones; or causes testicular atrophy in monkeys and dogs. A study from 2012 revives this idea, and finds some evidence in men living in the Niger delta area of Nigeria. In that study, 75 men who smoked marijuana were also likely to have shrunken testicles, infertility, and even male breasts.

The takeaway from all of this is that it’s really just too inconclusive. Each one of the 1980s studies found that while it may have altered certain factors that could lead to atrophy, the effects weren’t long lasting. Within 24 hours to three days, testicles began to grow back to normal size. So, if you’re really worried about whether your marijuana use is causing your balls to shrink, it’s probably best to stop. But it seems that continuing might only have temporary effects, if any at all.

All of this is surely informative, and may help at hinting what’s causing your testicles to shrink. But if you suspect you have testicular atrophy, the best thing you can do is to consult a doctor. We mean it.