Sleep a Key to Staying Young
- By Delthia Ricks Staff Writer : Newsday

Aging in men is intimately tied to how well they sleep, according to a new study which found that the shorter the periods of deep slumber become with time, the less likely it is that men , will produce a vital hormone associated with youth and vigor. Reporting in today's Journal of the American Medical Association, researchers at the University of Chicago " say the first stage of sleep decline in men occurs between the ages of 25 and 45, and with that loss comes a significant drop in the growth hormone. , By sleep decline, researchers mean that slumber is becoming increasingly fragmented, that men are likely to spend more time in lighter phases of sleep or are remaining wide awake during the wee hours of the night. With a decrease in growth hormone, c-1 which is triggered in sleep and primarily flows at night, men are subject to losing muscle mass and strength.
In its place, cortisol, produced by the adrenal glands, begins flowing in the evening. An elevation of evening cortisol levels, according to the study, is a hallmark of aging. Cortisol, a "fight or flight" hormone, heightens attention .i
and alertness, which becomes a problem when it's time to sleep. Eve Van Cauter, a professor of medicine at the university and.lead investigator of the research says the study maps the chrnonolgy of age-related changes in sleep duration and quality. And it focuses on men because of the key role growth hormone plays in muscular growth, strength and maintenance of their stamina.

"Altered levels of certain hormones may be a consequence of sleep decay," Van Cauter said.
Her study explored sleep patterns in 149 men between the ages of 16 and 83. Slumber was measured electronically in all-night polygraphic sleep recordings. Test subjects remained recumbent in bed in darkness for a least
eight hours. Daytime napping was not allowed. Hormone levels were measured by blood tests.

The initial stage of sleep deterioration, Van Cauter and colleagues found, comes early in life for men, usually by age 25 and continues into mid-life. Althougn total sleep remains constant , as young adults moved into mid-Iife, , the proportion of slow-wave, or deep : steep, decreased from nearly 20 precent of a normal night's sleep for those under 25 to less than 5 percent for I those over 35. By 45, the study showed, most men had lost the ability to maintain a significant length of deep sleep. Even though women were not part of the study, Van Cauter and colleagues, citing other investigations, said there is not a corresponding loss of deep-sleep patterns in women at such an early age, However, sleep fragmentation is common in both genders by old age.

Van Cauter suggests hormone re- placement for men as a solution to the lack of growth hormone that occurs with age, "We begin estrogen replacement as soon as women enter menopause, not 20 years later," she added.
If men go through a loss of growth hormone between 25 and 45, she asked, why should doctors wait 20 years to initiate treatment?

Even modest elevations in evening cortisol levels can contribute to memory deficits and insulin resistance, the study found. Insulin resistance is a characteristic of Type 2 diabetes, which usually occurs in middle age. Moreover, they found, elevated levels of evening cortisol may even promote awakenings.
"This is pretty exciting, just knowing that there is a relationship between sleep and the secretion of a hormone, which plays a role in stamina and muscle strength," said Catherine ; Pabst, a research associate in the sleep laboratory at Johns Hopkins University in Baltimore.

It used to be that people thought that sleep was something you did when you tired out at the end of the day," Pabst added. "Now we know that there are a lot of dynamic things going on and we are just beginning to scratch the surface.