Christmas food for thought: the gains and pains of laughter

As Christmas approaches like a freight train I, like many, scramble to buy last minute gifts and prepare myself to gorge on feasts and booze and laughter(?) – all part of a joyous(??) family gathering. In last effort to procrastinate until the very end, I present to you this short series of posts on various and totally random holiday-related themes. Enjoy!

Sings: Petri dish sterilizing near an open fire, lab rats nipping on my shoe, data woes cried by grad students, and PIs dressed like You-Know-Who! Ok, this might’ve gotten a laugh out of grad students. Anyone? I’ll show myself out.

Laughter permeates holiday gatherings. Dubbed “grooming at a distance”, laughter is thought to establish and maintain bonds between individual primates of all sorts. Like yawning, the mere sound of laughter often triggers giggling fits in others in a contagion-like manner. Within four-tenths of a second after exposure, electrical activity spreads out through areas involved in cognition, emotion, sensation and movement; this triggers facial contortions, spasmodic breathing and bodily convulsions as we involuntarily emit a series of curious vocalizations, ready to infect another.

Collapsing in a quivering heap, we are left under-the-influence of a deluge of a neuroendocrine cocktail. The amount of epinerphrine, a hormone in the fight-or-flight response plummets, while dopac, a major metabolite of dopamine, shoots up. Laughter also triggers the release of pain-relieving endorphins and growth- and metabolism-boosting growth hormone, which together with other chemicals form somewhat of a panacea for the mind and body. As Robert Burton once astutely wrote in 1621, “Mirth…prorogues life, whets the wit, makes the body young, lively and fit for any manner of employment.”

So where’s the evidence?

British Medical Journal produced a snicker-inducing, tongue-in-cheek report that synthesized findings from 785 papers on the health benefits of laughter. To round things up, they threw in harmful effects for good measure, while discarding papers written by authors with “Laugh” in their last name which where nonetheless “not particularly amusing”. Here’s what they found.

In terms of the psyche, laughter increased tolerance to pain in the lab, but hospital clowns did not reduce distress in children going through minor surgery to any observable extent. Humorous movies had minimal success on serious mental illnesses like schizophrenia, and group-based humor therapy did not particularly benefit late-onset depression in Alzheimer’s disease, though there was some improvement in patient morale and mood. Laughter was associated with life-long satisfaction, but there’s no evidence that one causes the other either way.

More mirthful news comes from laughter’s effect on the body. A 20min funny movie acutely reduced the stiffness of blood vessels and made them more limbre. A sense of humour lowers your risk of heart attack and improved lung function in those with chronic obstructive pulmonary disease, an illness that makes it difficult to breathe. In the latter case the credit goes to hospital clowns, whom apparently until the year of study (2008) were still regarded by some brave souls as non-terrifying entities.

Laughter had no consistent effects on immune functions such as natural killer cells, but sometimes aided the surgical removal of a pouch of pus by bursting it through laughter-generated muscle contractions. Laughter also benefits metabolism: compared to a monotonous lecture that drooled forever on, a comedy show helped control blood sugar levels after a meal. A 15min-bout of genuine laughter burns up to 40 calories, so battling the average 6000-calorie Christmas dinner would requires 37.5hrs of merriment to burn off. Better get those jokes ready.

Finally, if you’re trying to get pregnant through in vitro fertilization (test-tube baby), perhaps consider hiring a clown dressed like a chef de cuisine. In one study, such a clown entertained 110 would-be mothers after embryo transfer for 12-15 minutes with saucy jokes and magic tricks, “a recipe of success” that led to ~16% increase in pregnancy rate compared to the 109 non-clowned controls, adding another win for medicinal clowning.

Unfortunately laughter is not without its pains. Laughter weakens resolve and promotes your preference for certain brands, so keep a skeptic eye on that joke-cracking salesman. A hearty guffaw can cause temporary loss of consciousness, perhaps due to the sudden increase in pressure in the chest cavity that triggers a neural response. Laughing can screw up the electrical activity in the heart causing it to pump irregularly, to the point of cardiac arrest or rupture, giving “dying of laughter” a more sinister undertone.

Laughter can lead to abnormal collection of gas between the lung and chest wall or engorgement of air sacs of the lungs, resulting in labored breathing. The sharp intake of air to initiate laughter can promote inhaling foreign objects, causing you to choke on a small piece of turkey, while frequent exhaling disseminates infection. Laughter may also wreck havoc on your alimentary canal, dislocating the jaw or puncturing the esophagus (your “food-tube”), so maybe eat first and laugh later. You might also want a clear line to the wash(bath)room. Laughter can cause incontinence stemming from involuntary contractions of bladder muscles, which surprisingly may be counteracted by Ritalin.

And finally, uproarious laughter may not be so funny to your brain. Cataplexy, a condition where a person suddenly looses muscle tone, can be triggered by laughter and other salient stimuli, leaving you unceremoniously collapsed under the Christmas tree. That is, unless only one side of you is affected. In one documented case, laughter triggered cataplexy only on the right side of a patient’s body, leaving her presumably capable of continuing laughing on the left side of her face.

Laughter and other pleasurable things may precipitate headaches in the unfortunate, sometimes due to sacs of jello-like material in the third ventricle, a fluid-filled compartment in the brain. Laughter may also be no laughing matter to people with patent foramen ovale (PFO), whom have a hole in the heart that should’ve closed after birth but didn’t. Take this case for example: after 3 minutes of roaring laughter, a PFO patient lost her words (literally) and had a stroke.

This report from BJM obviously shows that laughter is not all beneficial, but it overall carries a low risk of harm in the general population. In terms of cost-benefit analysis a good laugh is still beneficial. Yet, as always, more research calls. As the authors put it:

“It remains to be seen whether, for example, sick jokes make you ill, if dry wit causes dehydration, or jokes in bad taste cause dysgeusia (note: distortion of the sense of taste), and whether our views on comedians stand up to further scrutiny.”
R E Ferner, & J K Aronson (2013). Laughter and MIRTH (Methodical Investigation of Risibility, Therapeutic and Harmful): narrative synthesis BJM DOI: 10.1136/bmj.f7274