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.