11 Scientific Benefits of Having a Laugh

iStock.com/Petar Chernaev
iStock.com/Petar Chernaev

They say that laughter is "the best medicine," and as it turns out, there is some scientific truth to this assertion. Humor-associated laughter has numerous health benefits, so here are 11 reasons you should laugh it up.

1. Laughter is a sign of good will toward others.

Group of friends laughing in a restaurant
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Laughter may be unique to humans. Why do we do it? According to a 2010 study in BMC Complementary and Alternative Medicine, laughter and smiling are generally intended as a message of good will. The authors extrapolate that there is a similar function in primates, who use facial expressions with bared teeth to suggest friendliness and sociability. They write, "Because some forms of smiling are voluntary and easily faked, laughter, which requires a more synergetic contraction of the wider musculature, is believed to have evolved in humans to express a secure, safe message to others."

2. Laughter may reduce your blood pressure.

Two girls laughing in a car
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High blood pressure (hypertension) is one of the most dangerous side effects of stress, as well as a huge risk factor for heart disease and stroke. However, it's hard to be stressed when you're laughing, so researchers have investigated whether laughter can bring blood pressure down. There are more than a few studies that show a reduction of blood pressure after laughter, such as a 2017 study in the Journal of Dental and Medical Research, where 40 patients undergoing hemodialysis listened to CDs of comic shows for 16 30-minute sessions over eight weeks, and saw a decrease in blood pressure.

In 2011 researchers presented results of a three-month-long study at the American Heart Association's Scientific Sessions. Researchers exposed 79 participants to either a music or laughter therapy. Laughter was stimulated through "playful eye contact" and breathing exercises. Immediately after sessions, the blood pressure readings from the laughers lowered by 7 mmHg—(millimeters of mercury, how the blood pressure readings on a sphygmomanometer are abbreviated). In comparison, music therapy only brought blood pressure down by 6 mmHg.

After three months, the blood pressure readings significantly decreased overall by 5 mmHg among the laughers. People in the comparison group showed no change in blood pressure readings.

3. This had led to a treatment known as laughter yoga.

group laughing in a workout class
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The success of laughter studies on blood pressure and other ills has led to a unique kind of treatment known as "laughter yoga."

Dr. Madan Kataria, founder of the Laughter Yoga School, told Medscape, "You don't need any jokes, any humor, or any comedy. You don't even need to be happy. What we do is laugh in a group and initiate laughter as a form of bodily exercise, but when we have eye contact with others, this laughter becomes real and contagious."

Kataria led a study of 200 male and female individuals who participated in laughter yoga sessions for 20 to 30 minutes. The researchers stimulated laughter in the participants for between 45 seconds and one minute, followed by deep breathing and stretching for the duration of the sessions.

Subjects who laughed saw a reduction in their systolic blood pressure of more than 6 mmHg, a significant change from baseline and also significant when compared with a non-laughing control group. Diastolic blood pressure was also significantly reduced. In addition, their levels of cortisol, a stress hormone, were also reduced.

As a result, laughter yoga has gone on to be used as an intervention for a variety of health issues, ranging from stress to dementia.

4. Laughter can reduce anxiety and other negative emotions.

Two guys laughing and shaking hands
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A 1990 study in Psychological Reports looked at the effects of humorous laughter on threat-induced anxiety. Researchers led 53 college students to believe (falsely) that they were going to receive an electric shock after a waiting period.

Subjects in the experiment group listened to a humorous tape while waiting for their shock. The placebo group listened to a non-humorous tape, and the control group did not listen to any tape. The humor group reported that their anxiety decreased during the anticipatory period, and those with the highest self-reported level of sense of humor had the lowest reported anxiety.

Laughter therapy has also been shown to improve anxiety in patients with Parkinson's disease [PDF], reduce anxiety and depression in nursing students, and improve optimism, self-esteem, and depression in menopausal women.

From a general psychological perspective, author Bernard Saper suggests in a paper for Psychiatric Quarterly that the ability to maintain a sense of humor and the ability to laugh can act as positive coping mechanisms to help a person get through difficult times.

5. Laughter is an immune booster.

Mom and boy laughing on couch
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At the beginning of cold and flu season, it may be a good idea to practice some laughter therapy, as several studies have shown the immune boosting power of a chuckle.

In one 2015 study on postpartum mothers in the Journal of Alternative and Complementary Medicine, researchers tested hand-expressed breast milk for immunoglobulin (IgA, antibodies that play an important role in immune function) before and after laughter therapy.

Twice a week, participants engaged in group "laughter dance routines" and some light breast massage while inducing laughter. Mothers who participated in the laughter therapy saw a small increase in their IgA. However, even a small amount was significant to the researchers, given that the postpartum period is when natural IgA in breast milk declines (it is at its highest level right after delivery, in the earliest, nutrient-dense breast milk known as colostrum).

Another study with college students found that watching funny movies increases salivary IgA (sIgA). Researchers have also found small examples of laughter's ability to increase the body's natural killer cells (NKs), a type of lymphocyte that is easy to test for in the blood. One study in the American Journal of Medical Science, albeit small—a cohort of only 10 male subjects—found significantly increased NK cell activity in the experimental group. Additional studies have shown increases in NK cell activity after laughter therapy or humorous videos, but most of these studies were done on male subjects.

6. Laughter may act as a natural anti-depressant.

woman laughing with dog
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While nobody would recommend laughter in lieu of other treatment for depression, it has shown promise at ameliorating depressed moods. Patients in long-term care facilities often suffer from depression and poor sleep, so a 2017 study in the Korean Journal of Adult Nursing [PDF] tested the effects of laughter therapy on 42 residents of two long-term care hospitals. The results were promising.

The laugher therapy, which the subjects undertook over eight sessions, for 40 minutes twice a week, included "singing funny songs, laughing for diversion, stretching, playing with hands and dance routines, laughing exercises, healthy clapping, and laughing aloud."

The results showed reduced depression and general mood improvement as well as improved sleep in the experiment group compared to the control group.

Another 2015 study in the Journal of Alternative and Complementary Medicine found that three 60-minute laughter therapy sessions improved the depression and negative mood states of cancer patients.

7. You breathe better after laughing.

grandfather and grandson laughing on ground
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It turns out that a good bout of deep belly laughter can lead to increased heart rate, respiratory rate, and oxygen consumption, which are similar to what happens during exercise. While a 2009 study in the International Journal of Humor Research found that these changes only last as long as the laughter itself, if you can laugh like that for 30 minutes to an hour, maybe you can skip the gym.

8. Laughter is good for your cardiovascular system.

women laughing at a movie
iStock.com / Jacob Ammentorp Lund

Your lungs aren't the only organ that benefits from a great guffaw. A 2009 study in Medical Hypotheses found powerful benefits to the heart and cardiovascular system.

Study participants watched either a comedy like Saturday Night Live or the bleak opening sequence of Saving Private Ryan, which is known to increase mental stress. They used a technique called brachial artery reactivity testing (BART), a form of ultrasound that looks at the brachial artery. Participants who watched the stressful movie experienced a 35 percent reduction in flow-mediated vasodilation (FMD, or how blood vessels dilate and contract); sluggish FMD is a risk factor for atherosclerosis. Meanwhile, the group that watched the funny scene saw a 22 percent increase in FMD, comparable to exercise. In short, laughing helped their blood flow better.

The American Heart Association recommends laughter for a healthy heart, adding that research has shown laughter promotes reduced artery inflammation and increased production of HDL, or "good" cholesterol.

9. Laughter calms stress hormones.

man and woman laughing
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Humor, and by extension, laughter, stimulates multiple physiological systems that decrease levels of stress hormones, such as cortisol and epinephrine, and increase the activation of the dopamine-dispensing reward system of the brain, according to researchers of a 2017 study in Advances in Physiology Education. A 2003 study in Alternative Therapies in Health and Medicine found that viewing a funny film decreased a wide variety of stress hormones.

10. Social laughter can relieve pain.

Girl with broken arm laughing in doctor office
iStock.com/Steve Debenport

Laughter might be as good as some analgesics for pain, something early physicians seemed to understand. In the 14th century, French surgeon Henri de Mondeville used humor to distract patients from the pain of surgery and to help them during recovery.

More modern research has found that participants who watched comedy videos needed less pain medication than those who watched control videos. In a 2011 study published in the Proceedings of the Royal Society, over the course of six experiments using extreme cold as a pain-tolerance measure, researchers found that social laughter—laughter done in groups in a social context—elevates pain thresholds. The authors suggest, "These results can best be explained by the action of endorphins released by laughter."

11. Laughing burns calories.

Woman laughing on a running trail.
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As if all of these benefits aren't a good enough reason to giggle every day, a 2014 study in the International Journal of Obesity found that laughter can burn calories. Researchers broke a group of 45 participants into two groups, half of whom watched film clips intended to evoke laughter for approximately 10 minutes, and half who watched film clips unlikely to stimulate laughter. Both groups were attached to a "calorimeter" that measured energy expenditure and heart rate. They determined that those who laughed during their viewing burned up to 10 calories in 10 minutes, as compared to those who did not laugh and did not burn any calories.

The Reason Our Teeth Are So Sensitive to Pain

This woman's tooth pain is actually helping her avoid further damage.
This woman's tooth pain is actually helping her avoid further damage.
champja/iStock via Getty Images

On a good day, your teeth can chew through tough steak and split hard candy into pieces without you feeling a thing. But sometimes, something as simple as slurping a frosty milkshake can send a shock through your tooth that feels even more painful than stubbing your toe.

According to Live Science, that sensitivity is a defense mechanism we’ve developed to protect damaged teeth from further injury.

“If you eat something too hot or chew something too cold, or if the tooth is worn down enough where the underlying tissue underneath is exposed, all of those things cause pain,” Julius Manz, American Dental Association spokesperson and director of the San Juan College dental hygiene program, told Live Science. “And then the pain causes the person not to use that tooth to try to protect it a little bit more.”

Teeth are made of three layers: enamel on the outside, pulp on the inside, and dentin between the two. Pulp, which contains blood vessels and nerves, is the layer that actually feels pain—but that doesn’t mean the other two layers aren’t involved. When your enamel (which isn’t alive and can’t feel anything at all) is worn down, it exposes the dentin, a tissue that will then allow especially hot or cold substances to stimulate the nerves in the pulp. Pulp can’t sense temperature, so it interprets just about every stimulus as pain.

If you do have a toothache, however, pulp might not be the (only) culprit. The periodontal ligament, which connects teeth to the jawbone, can also feel pain. As Manz explains, that sore feeling people sometimes get because of an orthodontic treatment like braces is usually coming from the periodontal ligament rather than the pulp.

To help you avoid tooth pain in the first place, here are seven tips for healthier teeth.

[h/t Live Science]

Arrokoth, the Farthest, Oldest Solar System Object Ever Studied, Could Reveal the Origins of Planets

NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko
NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko

A trip to the most remote part of our solar system has revealed some surprising insights into the formation of our own planet. Three new studies based on data gathered on NASA's flyby of Arrokoth—the farthest object in the solar system from Earth and the oldest body ever studied—is giving researchers a better idea of how the building blocks of planets were formed, what Arrokoth's surface is made of, and why it looks like a giant circus peanut.

Arrokoth is a 21-mile-wide space object that formed roughly 4 billion years ago. Located past Pluto in the Kuiper Belt, it's received much less abuse than other primordial bodies that sit in asteroid belts or closer to the sun. "[The objects] that form there have basically been unperturbed since the beginning of the solar system," William McKinnon, lead author of one of the studies, said at a news briefing.

That means, despite its age, Arrokoth doesn't look much different today than when it first came into being billions of years ago, making it the perfect tool for studying the origins of planets.

In 2019, the NASA spacecraft New Horizons performed a flyby of Arrokoth on the edge of the solar system 4 billion miles away from Earth. The probe captured a binary object consisting of two connected lobes that were once separate fragments. In their paper, McKinnon and colleagues explain that Arrokoth "is the product of a gentle, low-speed merger in the early solar system."

Prior to these new findings, there were two competing theories into how the solid building blocks of planets, or planetesimals, form. The first theory is called hierarchical accretion, and it states that planetesimals are created when two separate parts of a nebula—the cloud of gas and space dust born from a dying star—crash into one another.

The latest observations of Arrokoth support the second theory: Instead of a sudden, violent collision, planetesimals form when gases and particles in a nebula gradually amass to the point where they become too dense to withstand their own gravity. Nearby components meld together gradually, and a planetesimal is born. "All these particles are falling toward the center, then whoosh, they make a big planetesimal. Maybe 10, 20, 30, 100 kilometers across," said McKinnon, a professor of Earth and planetary sciences at Washington University. This type of cloud collapse typically results in binary shapes rather than smooth spheroids, hence Arrokoth's peanut-like silhouette.

If this is the origin of Arrokoth, it was likely the origin of other planetesimals, including those that assembled Earth. "This is how planetesimal formation took place across the Kuiper Belt, and quite possibly across the solar system," New Horizons principal investigator Alan Stern said at the briefing.

The package of studies, published in the journal Science, also includes findings on the look and substance of Arrokoth. In their paper, Northern Arizona University planetary scientist Will Grundy and colleagues reveal that the surface of the body is covered in "ultrared" matter so thermodynamically unstable that it can't exist at higher temperatures closer to the sun.

The ultrared color is a sign of the presence of organic substances, namely methanol ice. Grundy and colleagues speculate that the frozen alcohol may be the product of water and methane ice reacting with cosmic rays. New Horizons didn't detect any water on the body, but the researchers say its possible that H2O was present but hidden from view. Other unidentified organic compounds were also found on Arrokoth.

New Horizon's flyby of Pluto and Arrokoth took place over the course of a few days. To gain a further understanding of how the object formed and what it's made of, researchers need to find a way to send a probe to the Kuiper Belt for a longer length of time, perhaps by locking it into the orbit of a larger body. Such a mission could tell us even more about the infancy of the solar system and the composition of our planetary neighborhood's outer limits.

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