Friday, May 04, 2012

Everybody yawns from unborn babies to the oldest great-grandparent. Animals do it, too. But why, exactly, do people and animals yawn? Dr. Edward Hill discusses yawning in todays 60 Second Housecall.

Dr. Hill:

Yawning is a very common act. Medical science is not quite sure why we yawn but there are many theories.

One theory is that a build-up of carbon monoxide or a low oxygen level in our blood triggers the yawning reflex.

Another theory is that yawning stretches the lungs and lung tissue. Stretching and yawning may be a way to flex muscles and joints, increase heart rate and feel more awake.

Others believe that yawning is a protective reflex to redistribute the oil-like substance called surfactant that helps keep lungs lubricated inside and keeps them from collapsing.

Yawning is frequently associated with sleepiness, boredom or stretching. It is most common just after awakening or just before bedtime. It normally lasts about six seconds. Yawning can be observed as early as the eleventh week of life. Yawning can help expand the lungs and equalize the pressure in the middle ear.

To prevent excess yawning, get plenty of sleep at night and physical and mental stimulation during the day.

For North Mississippi Medical Center, Im Dr. Edward Hill.