Friday, June 03, 2005

Computer Clinic - Health Tips

Sleep Longer and Live Longer

It is commonly said that good sleep refreshes the mind and body. But very few of us know why this is so.

In sleep studies it has been found that subjects spent about one-third of their time asleep, suggesting that most people need about eight hours of sleep each day. Individual adults differ in the amount of sleep they need to feel well rested. However, infants may sleep as many as 16 hours a day.

The daily cycle of life, which includes sleeping and waking, is called a circadian (meaning "daily") rhythm, commonly referred to as the biologic clock. Hundreds of bodily functions follow biologic clocks, but sleeping and waking comprise the most prominent circadian rhythm. The sleeping and waking cycle is approximately 24 hours. In complete darkness, with no clocks or other time cues, humans live on slightly longer than 24-hour cycles.

Humans are designed for day-time activity and night-time rest.
Additionally, there is a natural peak in sleepiness at mid-day, the traditional siesta time. In addition, daily rhythms intermesh with other factors that may interfere or change individual patterns:

The fraction-of-a-second-firing of nerve cells in the brain may be faster or slower in different individuals.
The monthly menstrual cycle in women can shift the pattern.

The response to light signals in the brain is an important key factor in sleep:
Light signals coming through the eyes reset the circadian cycle.
Light signals travel to a tiny cluster of nerves in the hypothalamus in the center of the brain, the body's master clock, which is called the supra chiasmatic nucleus or SCN.
This nerve cluster takes its name from its location, which is just above (supra) the optic chiasm, which is a major junction for nerves transmitting information about light from the eyes.
The approach of dusk each day prompts the SCN to signal the nearby pineal (like a pine cone) gland, a pea-sized gland that is located just above the middle of the brain, to produce the hormone melatonin.
The longer a person is in darkness the longer the duration of melatonin secretion. Bright light has another effect: it directly inhibits the release of melatonin.
During the day, the pineal is inactive; but when the sun goes down and darkness occurs the pineal gland begins to actively produce melatonin, which is released into the blood.
This usually occurs around 9:00 p.m. As a result, melatonin levels in the blood rise sharply and we begin to feel less alert. Sleep becomes more inviting. Melatonin levels in the blood stay elevated for about 12 hours all through the night before the light of day, when they fall back to low daytime levels by about 9:00 a.m.

Melatonin also appears to trigger the need to sleep. Melatonin that has been prepared artificially is prescribed by doctors for people suffering from insomnia.
Melatonin secretion peaks at age seven, then declines precipitously during adolescence. At about age 45, the pineal gland begins to shrink and loses the cells that produce melatonin. Hormone production becomes erratic such that by age 60, we only produce 50% of the amount that we made during our twenties. This age related decline in the pineal production of melatonin may be a large apart of the reason so many older people suffer sleep problems.

Melatonin also acts as the body's time-setting hormone. Melatonin secretion tends to (1) to induce deep sleep (2) and to resynchronize the hypothalamic pituitary (2a) adrenal, (2b) thyroidal (2c) and gonadol brain axes. When melatonin deficiency levels develop as a function of age, de-synchronization takes place between these three tri-partite brain functions. Lack of sleep and hence lack of melatonin makes us feel disoriented.
Because melatonin acts as a time-setter it is taken to treat jet lag.

Melatonin is a powerful ant-oxidant that also enhances the body's resistance to disease and cancer. It, therefore, enhances life-expectancy. In experiments conducted with rats it was found that when the pineal gland of older rats were replaced with that of younger rats the life of the former was extended to the remaining life expectancy of the latter.

So, if you want to live a long and healthy life go to bed early and get your free dose of melatonin.

COMPUTER CLINIC-a simple medical diagnostic tool for laymen