Tony Whitaker, age 14, of Santa Cruz, Calif., for his question:
WHAT IS THE BIOLOGICAL CLOCK?
Biological clock is a popular name given to a mysterious timing system that operates in plants and man and other animals. It keeps accurate time of days, weeks, months and even years. It also times the activities of living things to keep them in harmony with the regular changes in their surroundings.
Man’s biological clock times his periods of sleep and wakefulness and many body activities. Birds migrate, fish spawn and flowers blossom on schedules set by their built in clocks.
No one knows where this biological clock is located or how it works. Some scientists say that every living thing has its own built in timing system that operates independently. Others say that the clocks are set by the natural rhythms of the earth’s electromagnetic or gravitational forces. Still others say that forces both inside and outside the body are necessary to keep the clocks accurate.
Biological clocks keep track of rhythmic changes in the environment and seasons of the year. Many, and possibly all, living things seem to respond to these rhythmic changes.
Many of life’s rhythms are based on the day night cycle. Man is most active during the day and rests at night. Apes, bees, butterflies, and many other kinds of animals follow this schedule. On the other hand, bats, moths, owls, rats and others are active at night.
The biological clock in each kind of animal sets the schedule that is must suitable.
Biological clocks in man work on schedules essential to life and health. Many vital body processes are programmed for 24 hour rhythms. The functions of cells, glands, kidneys, liver and nervous system are all coordinated with each other and with the day night rhythm of the environment. Each is timed to operate when it can do the greatest good for the entire body.
As an example, body temperature varies about two degrees during a 24 hour period. This temperature is lowest during the nighttime rest period and higher during the day’s active period.
You become most aware of the biological timing system when you fly by jet to a different time zone.
A flight from St. Louis to Paris that leaves St. Louis in the late afternoon will arrive when Parisians are just getting up for breakfast. Your rhythmic system will still be working on St. Louis time. By Paris time, you will have insomnia at night and be sleepy during the day.
Your biological clock will rest itself, but it may take several days. As a result, your body functions are out of rhythm, your efficiency drops and you feel tired. This is called “jet lag” or “jet exhaustion.”
Plants show daily rhythms. They raise their leaves in the daytime and lower them at night. These rhythmic changes, called sleep movements, usually continue even when the plants are kept in caves or in other places where light and temperature do not change.
Biological clocks also set the schedules for yearly rhythms in living things. They control the sprouting of seeds and the hibernation and migration of some birds and other animals. And the clocks also seem important in helping birds, fish, crustaceans and insects to navigate.