There are few things more adorable than a newborn baby’s delicious yawn. My new granddaughter and her family are currently staying with us and little does this tiny bundle know how much joy she brings and how many pictures are snapped, every time she simply opens wide and yawns. Less adorable and dare not photographed are her mother and father’s yawns, the result of sleep deprivation and exhaustion.

Science has long explored the mystery of when and why we yawn. It turns out we begin yawning already in the womb, beginning at around 11 weeks gestation (or the first time the mother is in shul when the rabbi speaks). Lack of sleep and boredom are the assumed explanations, but some people also report yawning when they exercise, sing, or engage in other activities.

Perhaps the most puzzling part of yawning is how and why it spreads. You may have heard, or noticed yourself, that when one person yawns it sets off a domino effect of yawning. Researchers believes that contagious yawning is a product of the chameleon effect, the subconscious mimicry and imitation of the mannerisms, expressions and postures of those around us. They suggest it is an involuntary attempt to fit in and connect, perhaps even a display of empathy.

Dr. Elisabetta Palagi of the University of Pisa, Italy, has studied the chameleon effect on facial expressions, hand movements, foot shaking, yawning and speech patterns. Last month, she presented data that found the impact of the chameleon effect, not on an expression or movement, but on a behavior.

Palagi’s research found that when a group is together and one person looks at his or her phone, 50% of the other people will look at their phone within 30 seconds. Interestingly, only 0.5% of people looked at the phone when the trigger touched the phone without looking at it. “It’s paying attention to the phone that sets off the mimicry,” Palagi says.

We mistakenly think that our actions, choices, idiosyncrasies or even flaws are our own and affect only us. The truth is that we are actually wired to feel interconnected, we are designed to subconsciously connect and impact one another.

From yawning, to foot movements, to getting distracted or lost on a cell phone—our actions will be contagious to others.

But the chameleon effect doesn’t only work in negative ways. Nicholas Christakis, a professor at Harvard Medical School, found that misery is not alone in liking company; happiness is also contagious. Knowing someone who is happy makes you 15.3% more likely to be happy yourself. A happy friend of a friend increases your odds of happiness by 9.8%, and even your neighbor’s sister’s friend can give you a 5.6% boost.

According to Christakis’s research, “Your emotional state depends not just on actions and choices that you make, but also on actions and choices of other people, many of which you don’t even know.”

Just like yawning is contagious, so is smiling. When one person smiles, their whole world smiles with them. The Talmud (Shavuos 39a) teaches kol Yisroel areivim zah lazeh, all of the Jewish people are areivim – guarantors – one to the other. The simple translation of “areivim” in this context is “guarantor.” We are all responsible for one another. Because we are responsible to one another, if there is another Jew who has not yet fulfilled their mitzvah, I have not completely fulfilled mine, and I can repeat a blessing or mitzvah for them.

Rabbi Elimelech of Lizhensk, has another interpretation. He writes:

One must always pray for his friend, as one cannot do much for himself, for “One does not deliver oneself from imprisonment.” But when asking for his friend, he is answered quickly. Therefore, each one should pray for his friend, and thus each works on the other’s desire until all of them are answered. This is why it was said, “Jewish people are areivim, responsible and sweet for one another,” where areivim means sweetness, as they sweeten for each other by the prayers they pray for one another, and by this they are answered.

Rabbi Elimelech says the meaning of areiv is sweet and the Talmudic principle means we have a responsibility to sweeten one another’s lives. Be happy and positive around your home and at work and your family and colleagues will be happier. Concentrate, focus and have intent when davening and people around you will mimic and imitate your behavior.

Choose to smile, even when you don’t feel like it and your whole world will smile with you.