In addition to REM sleep there are four stages of sleep.

Stage 1: the drowsy time, where the body is in preparation for sleep, and where we still have some awareness of our surroundings. In this stage the brain waves are seen as theta waves, and from this early sleep we may be easily wakened.

Stage 2: the light sleep that is a low voltage sleep with brief bursts of activity known as sleep spindles and K-complexes.

Stage 3: a 15 minute period of true sleep before the deep sleep, and at this stage 50% of the EEG shows large voltage delta waves.

Stage 4: the deepest sleep. During this time most repair work is done by the body under the influence of maximal HGH secretion in men.

If we sleep the optimum 8 hours per night, then we have spent 200,000 hours in the sleep state by the age of 70 years. One colleague has remarked that if we could stay awake for just one extra hour each day, then we could have an extra 25,000 hours (about 3 years) of awake time. This could mean more reading time or more TV but could it also mean diminished secretions of HGH??

As we saw earlier, when sleep is fitful and broken, we tend to secrete less HGH into the bloodstream at night, bringing on the unwanted cycle poor sleep causing lower HGH levels, and lower HGH levels causing still poorer sleep.

Dr. Eve Van Cauter, a sleep researcher at the University of Chicago, believes that if the capacity for deep sleep can be restored in people as they age, then the aging process may be slowed. Further, she feels that impaired HGH secretion caused by insomnia in older men is responsible for premature aging.