Picture the human body as a big clock, or perhaps a conglomerate of clocks, all ticking in unison. All forms of life respond to the cycles of the sun, the moon and the changing seasons.

This is called the biological clock, or, to use a more scientific term, the circadian rhythm. The word “circadian” comes from the phrase “circa diem”, which means about a day.or twenty-four hours. Research has revealed that the body clock operates on atwenty-five hour schedule, but plants and animals have the ability to adjust their varying cycles to the twenty- four hour solar day.

This cycle is influenced by light and darkness. People have been aware of its existence for centuries, perhaps as long ago as four B.C. Research into circadian rhythm is referred to as chronobiology. Chrono refers to time.

Circadian rhythm keeps the body alert during daylight hours and helps it to relax when night falls. This inner clock will even awaken you if you forgot to set your alarm. Unfortunately, it will also awaken you on days when you could sleep in.

Many things can upset the rhythm of your body. One of these is called jet lag. This affects people who travel across several time zones, often arriving at their destination at an hour earlier than when they left home. Jet lag upsets the sleep\wake cycles, causes headaches, irritability and a general feeling of malaise.

Members of your favorite hockey, football or other sports team may suffer from jet lag when forced to travel from coast to coast for games. This may interfere with their game performance.

Shift workers also suffer from disrupted rhythm. They may find it difficult to change from day shift to night shift and back again, even with a day or two of leave between shift changes.

Cross country bus and truck drivers often drink copious amounts of coffee or resort to caffeine pills to keep them alert on the road. Sometimes a short pause and a walk in the fresh air is helpful. Freight train drivers may also find it difficult to adjust to a schedule that requires them to stay awake twenty-four hours or more.

Even staying up two or three hours passed your regular bedtime can cause problems. You may find it difficult to wake up in the morning or be irritable and have a dull headache the next day This is easily remedied by retiring at the same time every evening.

This is not so for a sleep disorder called delayed sleep phase syndrome. This syndrome is sometimes caused by a circadian rhythm abnormality. In this case, the sufferer is on a rhythm where his or her body wants to rest from about 4 am until noon instead of the hours of sleep familiar to most people.

Yet another form of sleep disorder caused by the disruption of the circadian rhythm is Seasonal Affective Disorder ( SAD). This is also known as the “Winter Blahs.” With the arrival of autumn and winter, shorter days and a reduction in the number of hours of sunlight, some people experience depression and disturbed sleep patterns. People living in northern regions such as northern Canada and Alaska are especially at risk. The far north is sometimes called “The Land of the Midnight Sun.” In summer, days go by when the sun never, or barely, sets. Unfortunately in winter, the cycle is reversed and days go by in total darkness, or with the sun a momentary red glow on the horizon. This can severely hamper the operation of the body’s rhythm.

The ticking internal clock is controlled by the body’s production of melatonin. Melatonin is a hormone secreted by a small gland, the pineal gland, located in the middle of the head, between the two hemispheres of the brain. Melatonin is the oil that keeps your biological clock running smoothly.

As people age, the body produces less melatonin. This explains why the elderly often suffer from sleep disorders such as insomnia and daytime drowsiness.

The pineal gland is influenced by light. The hormone, melatonin, makes you sleepy, so the pineal gland slows production during daylight hours to keep you alert and increases production when darkness falls.

There are methods to combat things like the “winter blahs”. Special bright lights influence the pineal gland to slow production and thus promote daytime wakefulness. Bright rooms with walls painted white or sunny yellow may fool your body into believing it’s brighter than it actually is.

Sleeping pills have been in use for many years as an aid to sleep. However, sleeping pills should be used with care, as they can make you dependent, and then you can’t fall asleep without taking them. Good sleep hygiene, like a regular bedtime, helps to regulate the body clock. So does exercise, but do this earlier in the day, not in the evening when it will get the adrenaline flowing and only increase your sleeplessness.

Research is underway into the use of melatonin tablets as a sleep aid. The pros and cons of melatonin will be the subject of a future article.