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Maybe you've been here:. It's finals season, and you're walking across campus, when suddenly a big, beautiful sign catches your attention: Exam Week Therapy Dogs.

And when you show up, it's a giant room full of well-trained, adorable puppers and college students leaving with looks of stress-free bliss. Pet therapy has been around in some form or another for over a hundred years. And today, it's part of programs everywhere from hospitals to college campuses.

Many studies have shown that it works, too, and that pets can relieve anxiety, stress, and provide comfort. But these effects don't just happen because animals are cute. Instead, they actually say a lot more about what it means to be human.

Although it likely existed in some form before then, pet therapy was first popularized around 1860, thanks to the famous nurse Florence Nightingale. She noticed that patients with chronic illness felt better when they had an animal partner by their side. Now, these programs can be found basically everywhere there are people.

The technical term for this treatment is animal-assisted therapy, or AAT. There are all kinds of variations, but two are especially common:. In one type of program, a handler will bring an animal to an outside location, like a college campus or nursing home, for people to interact with.

The other kind is more structured and often involves a counselor or social worker. This type of therapy can include everything from playing with a dog to caring for a horse, and it's often combined with other forms of treatment depending on the patient. Regardless of the program, though, multiple studies have shown that AAT has a positive, measurable effect, both in those with and without clinical conditions.

For example, several have shown that petting and playing with a dog can improve patients' moods by decreasing their distress and pain. Specifically, a visiting dog can boost your body's production of endorphins, which ultimately trigger the release of chemicals that act like painkillers and produce euphoria. Dog visits have also been shown to decrease levels of cortisol, norepinephrine, and epinephrine in patients, which are all stress hormones.

Like most things in science, there are some papers that haven't found such significant results. But for the most part, researchers are pretty confident that AAT works. It just might not be because of the reasons you'd think.

For one, these effects don't just apply to animal lovers: They appear in people who feel neutral about animal companions, too. And it's not just because the animals are super outgoing and always excited to see you, either, like dogs typically are. Pretty much all animal companions do the trick for these kinds of therapies.

Rabbits, horses, cats … you name it! Even animal farms full of goats and cows are helpful. The effects aren't even because these animals are soft or fluffy.

Several studies have also shown that fish, bearded dragons, and crickets can help increase focus and positive emotions. Instead, the secret to AAT seems to be about the bond between humans and animals in general. After all, whether you're sick, stressed, or just trying to process life, animal companions won't judge you.

But they will be there for you. Most studies have focused on AAT's effects and not the underlying mechanism, so it's hard to say for sure that this is the case. And it probably varies depending on the person and the animal, too.

But in general, an unconditional, non-judgmental relationship with animals could give patients a safe place to process emotions or try new tasks. One study also suggested they could be a helpful distraction from other problems or symptoms, or a place to practice social interactions. And there is some evidence for the importance of the human-animal relationship in studies that have been done so far.

In a study published in the journal of Anxiety, Stress and Coping in 2003, 58 people without clinical diagnoses were presented with a stressful situation: They were told that they might be asked to hold a tarantula sitting elsewhere in the room. Those who considered this while petting an animal — whether it was a soft, fluffy rabbit or a hard-shelled turtle — experienced a reduction in stress and anxiety. But those who were petting a plush toy version of those animals didn't display the same effects.

Which makes sense, if the relationship and interactions with the animal are key. On the flip side, though, other studies with dementia patients have shown that robot dogs are effective at reducing stress and anxiety. These robots looked, sounded, and behaved a lot like the real thing, and the patients responded to them a lot like they did with real animals.

So the benefits of the relationship were probably replicated — unlike with the plush toys in the other study. It would help to have some solid research to pin down this mechanism, but it seems like a promising one. Of course, there are other positive side effects of being around animals, too.

Like, playing with a dog or helping out at an animal farm will increase your amount of physical activity, and exercise is a well-known way to boost your endorphin levels. But at the end of the day, when it comes to animal-assisted therapy, it seems to be mostly about the bond. Thanks for watching this episode of SciShow Psych!

You might love hanging out with your dog, but have you ever wondered if they actually love you back? Don't worry; we've got an episode for that. [♪ OUTRO ].