Editing Laughter (section)

== Health ==
A link between laughter and healthy function of blood vessels was first reported in 2005 by researchers at the University of Maryland Medical Center with the fact that laughter causes the dilatation of the inner lining of blood vessels, the [[endothelium]], and increases blood flow.<ref>{{cite journal | last1 = Miller | first1 = M | last2 = Mangano | first2 = C | last3 = Park | first3 = Y | last4 = Goel | first4 = R | last5 = Plotnick | first5 = GD | last6 = Vogel | first6 = RA | year = 2005 | title = Impact of cinematic viewing on endothelial function | journal = Heart | volume = 92 | issue = 2| pages = 261–2 | doi=10.1136/hrt.2005.061424| pmid = 16415199 | pmc = 1860773 }}</ref> Drs. Michael Miller (University of Maryland) and William Fry (Stanford) theorize that beta-endorphin-like compounds released by the hypothalamus activate receptors on the endothelial surface to release [[nitric oxide]], thereby resulting in dilation of vessels. Other cardioprotective properties of nitric oxide include reduction of inflammation and decreased platelet aggregation.<ref>{{cite journal | last1 = Vlachopoulos | first1 = C | last2 = Xaplanteris | first2 = P | last3 = Alexopoulos | first3 = N | last4 = Aznaouridis | first4 = K | last5 = Vasiliadou | first5 = C | last6 = Baou | first6 = K | last7 = Stefanadi | first7 = E | last8 = Stefanadis | first8 = C | year = 2009 | title = Divergent effects of laughter and mental stress on arterial stiffness and central hemodynamics | journal = [[Psychosom. Med.]] | volume = 71 | issue = 4| pages = 446–53 | doi = 10.1097/PSY.0b013e318198dcd4 | pmid = 19251872 | s2cid = 36768384 }}</ref>

Laughter has various proven beneficial biochemical effects. It has been shown to lead to reductions in stress hormones such as [[cortisol]] and [[epinephrine]]. When laughing, the brain releases [[endorphins]] that can relieve some physical pain.<ref name="DunbarBaron2011">{{cite journal|last1=Dunbar|first1=R. I. M.|last2=Baron|first2=R.|last3=Frangou|first3=A.|last4=Pearce|first4=E.|last5=van Leeuwen|first5=E. J. C.|last6=Stow|first6=J.|last7=Partridge|first7=G.|last8=MacDonald|first8=I.|last9=Barra|first9=V.|last10=van Vugt|first10=M.|title=Social laughter is correlated with an elevated pain threshold|journal=Proceedings of the Royal Society B: Biological Sciences|volume=279|issue=1731|year=2011|pages=1161–1167|issn=0962-8452|doi=10.1098/rspb.2011.1373|pmid=21920973|pmc=3267132}}</ref> Laughter also boosts the number of antibody-producing cells and enhances the effectiveness of T-cells, leading to a stronger immune system.<ref name="Smith Lee" /> A 2000 study found that people with heart disease were 40 percent less likely to laugh and be able to recognize humor in a variety of situations, compared to people of the same age without heart disease.<ref>{{cite web|url=http://umm.edu/news-and-events/news-releases/2000/laughter-is-good-for-your-heart-according-to-a-new-ummc-study|title=Laughter is Good for Your Heart, According to a New UMMC Study|website=University of Maryland Medical Center|access-date=2014-11-04|archive-date=2017-09-06|archive-url=https://web.archive.org/web/20170906231702/http://www.umm.edu/news-and-events/news-releases/2000/laughter-is-good-for-your-heart-according-to-a-new-ummc-study|url-status=dead}}</ref>

Anecdotally, journalist and author [[Norman Cousins]] developed in 1964 a treatment program for his [[ankylosing spondylitis]] and [[collagen disease]] consisting of large doses of Vitamin C alongside laughter induced by comic films, including those of the [[Marx Brothers]]. "I made the joyous discovery that ten minutes of genuine belly laughter had an anesthetic effect and would give me at least two hours of pain-free sleep," he reported. "When the pain-killing effect of the laughter wore off, we would switch on the motion picture projector again and not infrequently, it would lead to another pain-free interval."<ref>Cousins, Norman, ''The Healing Heart : Antidotes to Panic and Helplessness'', New York : Norton, 1983. {{ISBN|0-393-01816-4}}.</ref><ref>Cousins, Norman, ''Anatomy of an illness as perceived by the patient : reflections on healing and regeneration'', introd. by [[René Dubos]], New York : Norton, 1979. {{ISBN|0-393-01252-2}}.</ref>