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If you feel down, or need a quick happy boost, a friendly tickle fight might help you out!

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[ ♪INTRO ].

There are all kinds of companies out there trying to sell you quick and easy ways to boost your mental health. The problem is, those rarely have scientific support.

But, there is one thing you can do to feel a little happier, and it's totally free: you can get tickled. Now, just to be clear, no one has done any randomized clinical trials to determine whether regular tickling improves mental health outcomes in people. But there's every reason to think that it would.

Though, when we say tickling, it's important to note that we mean the hard, poking-in-the-ribs kind of tickling that scientists call gargalesis. Weirdly enough, that's actually not what you'll get if you shell out for a session at a so-called “tickle spa,” which is a real thing that I was just informed of. They do the light kind of tickling, like tracing the skin with a feather, which is called knismesis — and, unfortunately, there just hasn't been much psychological study of that.

But there is a lot of research that suggests gargalesis can help you destress and feel happier. So one piece of evidence that you are feeling happier: you laugh. There are a number of theories as to why tickling makes you laugh, but regardless of why, you do laugh, and that can make you feel happier and less stressed.

Which we all need these days. Laughing induces the release of neurotransmitters like serotonin and dopamine in the hypothalamus — a part of your brain that, among other things, helps regulate your emotions. So basically, when you laugh, these neurotransmitters flood into your brain, making you feel euphoria and joy.

Laughter also decreases stress hormones in your blood. These molecules, like adrenaline and cortisol, are associated with what's often called your “fight or flight' response. That's when your heart rate begins to increase, your blood pressure rises, and your body begins to dump sugar into your bloodstream to give you the energy you need to fight or run.

Which is great, if you, y'know, actually need to fight or run. But if you are chronically stressed, these hormone levels remain high, which isn't great for you because it suppresses your immune system. That's why lowering them can make you healthier and happier.

And it turns out laughing is one way to do that. Many studies show that the act of laughing brings cortisol and adrenaline levels down temporarily. Some studies have even shown regular laughter increases the activity of immune cells in your body, making you less likely to get sick.

This probably has to do with those hormonal changes, like the lowering of cortisol. And there may be more to it, because laughter engages your diaphragm, which stimulates the flow of lymph — a fluid that moves your immune cells around the body. So the muscular action of laughing could help your body's defenders get to where they need to go more efficiently.

In fact, there are specific exercises used by psychologists to stimulate laughter because of its well-known therapeutic effects. So I guess it really is the best medicine! They say that for a reason!

And here's the thing, that's not all tickling's got going for it. Because… you can't tickle yourself. You have to be tickled by someone else.

That means that while you are being tickled, you're engaging in physical contact with someone. Hopefully, if you're agreeing to be tickled, you consider that kind of contact to be a good thing. And research overwhelmingly indicates how good positive touch can be for you.

You see, whenever someone touches you — whether its a positive touch, like a hug, or a negative touch, like a push — your body responds in a bunch of different ways. Positive touch lights up your brain's orbitofrontal cortex, a region associated with the value of rewards, and a part of the network involved in processing compassion and other positive emotions. So like laughter, positive touch gives your brain a happy surge of dopamine, plus it makes you feel more empathetic and connected to others.

Positive touch also releases neurotransmitters like oxytocin which can boost your mood and reduce blood pressure. So between laughter and positive touch, there's every reason to think tickling can boost a person's mood and their health. Though, the idea is still mostly theoretical because we haven't conducted a ton of tickle studies in people.

I don't know why! But it turns out we have done a lot of tickle research in animals, and those studies provide further support to this idea that it's good for mental health. Fun fact: rats also laugh when they're tickled — we just can't hear it because it's at such high frequency which is adorable.

And researchers have tickled rats a lot in the name of science. For example, a 2012 study showed that tickling rats increased their “optimism”. You see, the rats were trained to understand that one sound meant they were getting a treat, while another meant a shock was coming unless they pushed a lever.

Then, some of them were tickled. When presented with a new, intermediate sound, the tickled rats were more likely to think it meant a treat, so they didn't race to the lever to protect themselves from a shock. And if studies in rats are any indication, the effects of tickling may stick around long after you've been tickled.

A study published in 2013 found that rats that undergoing a stressful situation were less likely to have a fearful reaction if they had been tickled in the days leading up to the experience. This seemed to be due to tickling's stress hormone-lowering powers, as the tickled rats had significantly lower levels of adrenaline and noradrenaline than the rats who weren't tickled. What's more, these lower levels of stress hormones stayed that way at least 96 hours after the rats were stress tested — and that's just the longest that researchers looked!

So even though we haven't done similar trials in people, the science of tickling suggests that it can likely relieve stress and boost happiness to improve your overall well being. So if you're feeling a bit tense or if you need of a happy boost and the idea of a tickle fight appeals to you, go for it! And if you are a scientist, please do some research, I want to know!

I want to tickle booths all around my town! [ ♪OUTRO ].