Navigation Links
More than a sign of sleepiness, yawning may cool the brain
Date:9/19/2011

Though considered a mark of boredom or fatigue, yawning might also be a trait of the hot-headed. Literally.

A study led by Andrew Gallup, a postdoctoral research associate in Princeton University's Department of Ecology and Evolutionary Biology, is the first involving humans to show that yawning frequency varies with the season and that people are less likely to yawn when the heat outdoors exceeds body temperature. Gallup and his co-author Omar Eldakar, a postdoctoral fellow in the University of Arizona's Center for Insect Science, report this month in the journal Frontiers in Evolutionary Neuroscience that this seasonal disparity indicates that yawning could serve as a method for regulating brain temperature.

Gallup and Eldakar documented the yawning frequency of 160 people in the winter and summer in Tucson, Arizona, with 80 people for each season. They found that participants were more likely to yawn in the winter, as opposed to the summer when ambient temperatures were equal to or exceeding body temperature. The researchers concluded that warmer temperatures provide no relief for overheated brains, which, according to the thermoregulatory theory of yawning, stay cool via a heat exchange with the air drawn in during a yawn.

Gallup describes the findings as follows:

"This provides additional support for the view that the mechanisms controlling the expression of yawning are involved in thermoregulatory physiology. Despite numerous theories posited in the past few decades, very little experimental research has been done to uncover the biological function of yawning, and there is still no consensus about its purpose among the dozen or so researchers studying the topic today.

"Enter the brain cooling, or thermoregulatory, hypothesis, which proposes that yawning is triggered by increases in brain temperature, and that the physiological consequences of a yawn act to promote brain cooling. I participated in a study [published in Frontiers in Evolutionary Neuroscience in September 2010] that confirmed this dynamic after we observed changes in the brain temperature of rats before and after the animals yawned. The cooling effect of yawning is thought to result from enhanced blood flow to the brain caused by stretching of the jaw, as well as countercurrent heat exchange with the ambient air that accompanies the deep inhalation.

"According to the brain cooling hypothesis, it is the temperature of the ambient air that gives a yawn its utility. Thus yawning should be counterproductive -- and therefore suppressed -- in ambient temperatures at or exceeding body temperature because taking a deep inhalation of air would not promote cooling. In other words, there should be a 'thermal window' or a relatively narrow range of ambient temperatures in which to expect highest rates of yawning.

"To test this theory in humans, I worked with Omar Eldakar to conduct a field-observational experiment that explored the relationship between ambient temperature and yawning frequency. We measured the incidence of yawning among people outdoors during the summer and winter months in Arizona. Summer conditions provided temperatures that matched or slightly exceeded body temperature (an average of 98.6 degrees Fahrenheit) with relatively low humidity, while winter conditions exhibited milder temperatures (71 degrees Fahrenheit on average) and slightly higher humidity. We randomly selected 160 pedestrians (80 for each season) and, because yawning is contagious, had them view images of people yawning.

"Our study accordingly showed a higher incidence of yawning across seasons when ambient temperatures were lower, even after statistically controlling for other features such as humidity, time spent outside and the amount of sleep the night before. Nearly half of the people in the winter session yawned, as opposed to less than a quarter of summer participants.

"Furthermore, when analyzing data for each season separately, we observed that yawning was related to the length of time a person spent outside exposed to the climate conditions. This was particularly true during the summer when the proportion of individuals yawning dropped significantly as the length of time spent outside increased prior to testing. Nearly 40 percent of participants yawned within the first five minutes outside, but the percentage of summertime yawners dropped to less than 10 percent thereafter. An inverse effect was observed in the winter, but the proportion of people who yawned increased only slightly for those who spent more than five minutes outdoors.

"This is the first report to show that yawning frequency varies from season to season. The applications of this research are intriguing, not only in terms of basic physiological knowledge, but also for better understanding diseases and conditions, such as multiple sclerosis or epilepsy, that are accompanied by frequent yawning and thermoregulatory dysfunction. These results provide additional support for the view that excessive yawning may be used as a diagnostic tool for identifying instances of diminished thermoregulation."


'/>"/>
Contact: Morgan Kelly
mgnkelly@princeton.edu
609-258-5729
Princeton University
Source:Eurekalert  

Related medicine news :

1. Gadgets not related to teenagers brain pain
2. Dementia Rates Escalate as Brain Capacity Diminishes with Age
3. Researchers discover new way to kill pediatric brain tumors
4. Scientists Pinpoint Area of Brain That Fears Losing Money
5. Physical Changes in Brain Linked to Altered Spirituality
6. Pro Athletes Brains React at Olympic Speed
7. Neuroscientists reveal new links that regulate brain electrical activity
8. Brain Scan Shows What Beauty is Worth
9. Study supports alternative anti-seizure medication following acute brain injury
10. Exercise helps protect brain of multiple sclerosis patients
11. Pittsburgh Neurosurgeons Explore Use of Drug that Illuminates Brain Tumor Cells To Guide Surgery
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
More than a sign of sleepiness, yawning may cool the brain
(Date:10/13/2017)... (PRWEB) , ... October 13, 2017 , ... Apple ... care services, staged a mock evacuation of the facility as part of a disaster ... Fire Department, Echo Hose EMS and Shelton City Emergency Manager, as well as the ...
(Date:10/13/2017)... , ... October 13, 2017 , ... Global Healthcare Management’s ... Alexandria Park in Milford, NJ. This free event, sponsored by Global Healthcare Management’s ... The fun run is geared towards children of all ages; it is a ...
(Date:10/13/2017)... ... October 13, 2017 , ... “The Journey: From the ... danger possible to save lost souls in the Philippines. “The Journey: From the Mountains ... a dedicated teacher of the Bible. She has taught all ages and currently teaches ...
(Date:10/12/2017)... ... October 12, 2017 , ... Planet Fitness, one of the largest and ... plans to open a flagship location in Covington, LA at 401 N. U.S. Highway ... store next to Office Depot in the Holiday Square shopping center. Its location allows ...
(Date:10/12/2017)... ... 2017 , ... Asante, a nationally recognized health system in ... existing home health joint venture through an agreement, effective October 1, 2017, to ... home health company with Asante, delivering clinically integrated care, for the past eight ...
Breaking Medicine News(10 mins):
(Date:10/10/2017)... -- NDS received FDA 510(k) clearance in May 2017 for its highly ... designed for endoscopy environments. An innovative secondary monitor solution, ZeroWire ... support the improvement of patient outcomes, procedural efficiency, and the lowering ... ... ...
(Date:10/4/2017)... 4, 2017  South Korean-based healthcare product Development Company ... "cprCUBE" on Kickstarter. The device will educate the user ... with better efficiency compared to the dated and pricey ... on efficacy of the compression for a more informed ... goal to raise $5,000. ...
(Date:10/2/2017)... 2017  Eli Lilly and Company (NYSE: ... third quarter of 2017 on Tuesday, October 24, 2017. ... day with the investment community and media to further ... call will begin at 9 a.m. Eastern time. Investors, ... webcast of the conference call through a link that ...
Breaking Medicine Technology: