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Subject: Pause That Refreshes Eludes Explanation; In Fish or Freshmen, Yawn Is a
Date: Mon, 9 Nov 92 05:41:19 EST
Message-ID: <36.1992Nov9.054120@AmeriCast.com>

Pause That Refreshes Eludes Explanation; In Fish or Freshmen,
Yawn Is a Revving Up<By Boyce Rensberger<Washington Post Staff
Writer=

Reading this article and looking at the pictures are both likely
to increase your mental alertness. Or so one could conclude from
a leading theory on why people yawn.  Everybody knows that yawn-
ing is contagious. Seeing another person yawn, or even looking at
these photographs, can trigger the effect in many people. It be-
gins with that familiar tightening in the neck just under the jaw
and swells into a mouth-widening, chest-swelling inhalation and,
finally, a satisfying exhalation.

And, as many people notice, a little bit of a rush follows, a
brief sharpening of the senses.

That head-clearing effect, according to Ronald Baenninger, one of
the few scientists in the world to study yawning, is the best
guess as to why we yawn. It is a way of increasing mental alert-
ness when it matters. He notes, for example, that yawning is most
common just after people wake up and late at night when they're
trying to stay awake. Once people "give themselves permission to
fall asleep at night," he said, yawning ceases.Lecture Hall Ob-
servation<

"As everybody knows, people also yawn a lot when they're bored,"
said Baenninger, who teaches psychology at Philadelphia's Temple
University. "Classrooms and lecture halls are the absolute best
places to observe yawning."

Baenninger sees these all as instances in which subconscious
mechanisms in people's brains are trying to get them awake and
alert or to keep them that way. Nobody knows exactly what the
mechanism might be. Some suggest the mechanics of yawning improve
drainage of blood from the brain, allowing a brief surge of
fresh, oxygenated blood to enter. Others suspect the act may
somehow trigger the brain's production of stimulatory neuro-
transmitters, substances that relay signals from one brain cell
to another.

"It's not just people, either," he said. "All kinds of animals
yawn. Birds yawn. Even fish yawn. For a behavior to be that
widespread, it has to have a real purpose."

Baenninger said many animals yawn at the same times that people
do. Lions in the wild yawn in the early evening as they are get-
ting up from their daytime napping to prepare to hunt. Observa-
tion at the Philadelphia zoo shows that captive lions yawn most
just before feeding time.  "They're getting up for it," he said,
"the same as if they were going to hunt."

Mandrills, other baboons and laboratory rats also yawn a lot just
before feeding time. So do damselfish and "Siamese" fighting
fish, as do gulls, ostriches, rhinoceroses and hippopotamuses.

People who live with cats and dogs, Baenninger said, may notice
the same things. Dogs are well known to yawn - and to stretch, an
activity that can accompany yawning in many species - just as the
regular time for their walk approaches.

The only non-yawning vertebrate species Baenninger has found is
the giraffe. One of his graduate students spent 35 hours watching
zoo giraffes and never saw a yawn. Because of the great distance
between the head and both heart and lungs, giraffes have special
adaptations for breathing and blood circulation that Baenninger
speculates may obviate the need for yawning.

In all yawning species, the form of the event is consistent: The
mouth opens slowly as the intensity builds and then, after the
peak, it shuts quickly. Even the duration is consistent - five to
six seconds.

Baenninger said the alertness theory fits well with observations
of human yawning, a type of research that has not been easy to
do.

"The usual funding mechanisms of science don't take this stuff
seriously," Baenninger said. "Even I started this work almost as
a joke but it has turned out to be so fascinating that I keep it
up on my own. I don't ask for grant support."

Yawning is so neglected by the scientific establishment that
pharmacologist Alan Cowan had been studying the phenomenon for
years at Temple before he found out Baenninger shared his in-
terest. The two researchers constitute what may be the nation's
leading yawning research center. Cowan said there has never been
a scientific conference on the subject. "There was a three-day
international conference on scratching and grooming at the New
York Academy of Sciences a few years ago and a hundred scientists
came," Cowan recalled. "Yawning has never been taken that seri-
ously."

The research has also been difficult, Baenninger said, because
"when you bring people into the lab, they steadfastly refuse to
yawn. They're probably anxious and this could mean they don't
really need to yawn to keep alert." But when volunteers are put
in a room where they think they can't be seen - and are observed
through a one-way window - they yawn just as predicted.Examining
the Mechanics< Monitors show that the volunteers' heart rates go
up after a yawn, a standard sign of heightened physical alert-
ness. An indicator of mental arousal also rises - the galvanic
skin response. An instrument with electrodes measures the ability
of the skin to conduct a weak current. The more mentally aroused
a person is, the more the sweat glands exude salty liquid that
improves skin conductance.

How yawning might produce these effects, however, remains
elusive. One longstanding theory is that the muscle action of
yawning squeezes blood out of a rich network of veins in the
neck, sending it back to the heart and clearing the way for
freshly oxygenated blood to enter the brain.  Challenging this
view are experiments in which people breathe pure oxygen or
breathe faster - both of which boost the oxygen level of the
blood. They yawn as much as ever.

"There must be something a lot more complex going on," Cowan
said, "something apparently involving neurotransmitters."

Cowan said that yawning can be induced in people and other an-
imals by giving them a wide variety of substances known to alter
the complex network of interactions among neurons and neuro-
transmitters. For example, dopamine and other substances that
bind to dopamine receptors induce yawning. This fits with the ob-
servation that people with Parkinson's disease, in which the
brain loses its ability to make dopamine, rarely yawn.

"We used to think dopamine was the story," Cowan said, "but we
know now that many other things induce yawning and they act in
different "ays. We know less now than we thought we did a few
years ago." Even less clear is why yawning is contagious. Baen-
ninger speculates that this evolved as a way of synchronizing the
arousal states of all members of a social group. "When the leader
of a primate group gets up in the morning and yawns," he said,
"that gets the others going. It might be important to do this so
that they can all be ready to move together."

If Baenninger's theory is right, and if this story has had its
effect, you too should now be pumped up and ready to face the
day.<04:58 11-09C9999-----

Copyright 1992, The Washington Post.  This story is from the
Washington Post's Capitol Edition On-Line and is not to be ar-
chived or redistributed.

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