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
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,"
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
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.