Studies say smiles release stress-fighting neurochemicals, act as a natural pain reliever and more.

It is another Monday morning, and not much is going right. In fact, I feel the twin wolves of irritability and depression snapping at my heels. Summer sunshine and greenery have segued into rainy gloom. The last thing I feel like doing is smiling.

Even on the days you don't want to smile, you should. Smiling represents “an actual pause out of your head into your body and activates stress-fighting neurochemicals,” explains Columbus therapist, speaker and trainer, Nancy Jane Smith, author of “The Happier Approach: Be Kind to Yourself” and other books.

These stress-fighting chemicals include neuropeptides, tiny molecules that allow neurons to communicate with the rest of the body and facilitate the expression of emotion, releasing the feel-good neurotransmitters of endorphins, dopamine and serotonin.

A study reported in Canadian Family Physician noted that smiling and laughter can relieve anxiety in the most challenging situations, such as going to the dentist. In addition, smiling is a natural pain reliever and antidepressant. The release of serotonin serves as an antidepressant and a mood-lifter, while endorphins act as natural pain relievers. There are also reports that smiling is associated with a longer life span, in general.

If those aren't enough reasons to smile, there's more. According to some scientists, smiling can help you look thinner and even younger. “Studies have shown people who smile are viewed by others as more attractive, reliable, relaxed and sincere,” writes author, motivational speaker and brain injury survivor Debbie Hampton.

Smiling is contagious, in fact. When people perceive a facial expression in others, “they partially activate the corresponding emotional state in themselves,” according to recent research in Trends in Cognitive Sciences. So when dealing with a difficult situation with a coworker, for example, smiling at him or her “can help reduce stress in the moment,” notes Smith.

Smiling also lowers your heart rate and blood pressure, which is true of even fake smiles. A study at the University of Kansas showed lower heart rates after recovery from stressful activities from participants who were instructed to smile as opposed to those who weren't.

The most appealing and sincere smiles are, of course, best. A genuine smile, also known as a Duchenne smile for the neurologist who identified it, engages both the mouth and the eyes. A forced or standard smile—such as when someone asks you to pose for a photo or you're trying to be nice—only uses the muscles around your mouth. Sometimes a fake smile is better than none at all, according to some researchers.

All said, there are days that you may have trouble finding any reason to smile. “Sometimes smiling just isn't going to cut it,” Smith advises. “If you're having a hard day or something traumatic happens, it's better to try to cope directly with the situation and realize that you're going to be sad. There's no sense in beating yourself up over not smiling.”

Under normal circumstances, however, Smith says, “taking a deep breath or even touching your toes can help you get back into your body” and induce a smile. Even small reminders, such as putting sticky notes in various places, setting alerts on your phone or even using a favorite screen saver can remind you to smile.

“The point is to find something that engages your soul and slows you down so you can think about smiling,” she adds.

As I write, my cat Peabody jumps on my desk. Large and in charge, he knocks over pens, sits on my notes and loudly purrs, causing me to break out my best Duchenne smile.