Jewish World Review Feb. 22, 2002 /10 Adar, 5762
By Robert A. Wascher, M.D., F.A.C.S.
http://www.NewsAndOpinion.com --
PEOPLE who sustain a heart attack and experience the loss of heart function
outside of the hospital have a very poor chance of survival. The likelihood
of surviving cardiac arrest without serious brain damage is even lower
still.
Early experience with open-heart surgery showed that reducing the
body temperature of a patient can significantly decrease the risk of brain
injury caused by the loss of oxygen delivery (hypoxia) to the brain. Animal
studies of artificially induced cardiac arrest have also shown an impressive
reduction in subsequent brain injury, and death, in animals that were cooled
down after their hearts were stopped. However, the applicability of these
findings to humans has largely been left unexplored.
This week's New England Journal of Medicine includes a study, performed in
Australia, of 77 patients who were brought into the hospital following
cardiac arrest. After resuscitating the patients and restarting their
hearts, 43 of the patients' bodies were cooled to 33 degrees Centigrade
(normal body temperature is 37 degrees) for a period of 12 hours. The
remaining 34 patients did not undergo hypothermia (cooling) treatment.
The
researchers found that 49% of the hypothermia patients survived and had
minimal or nor brain damage secondary to their cardiac arrest. On the other
hand, only 26% of the patients who did not have their bodies cooled survived
with good neurological function.
After statistical analysis, the
researchers concluded that the lowering of body temperature increased the
chance of surviving a cardiac arrest with a good neurological outcome by
more than five-fold. The relatively small number of patients in this study
will mandate larger studies before any changes can be proposed in the
current treatment of patients with out-of-hospital cardiac arrest.
However,
if this study's results hold up after larger scale studies have been
performed, then it is very likely that hypothermic treatment will, someday,
become part of the standard treatment in such cases.
A SILVER LINING FOR THE CHRONICALLY SLEEP-DEPRIVED?
Six years later, the survey answers were
correlated with the death rate of the study participants. The study's
authors concluded that people who slept more than 8 hours per night, or 6 or
less hours per night, had a shorter lifespan than people who slept 6 to 7
hours per night.
The risk of earlier death was most significant among
volunteers reporting more than 8.5 hours of sleep per night and those who
slept for less than 3.5 to 4.5 hours per night.
This study was widely reported in the press last week as evidence that mild
sleep deprivation could possibly prolong one's life, while the traditionally
observed "8 hours a night" sleep rule was actually associated with earlier
death. Although the study controlled for other common causes of early death
(such as smoking, obesity, and exercise habits), it has several significant
weaknesses in terms of the validity of its conclusions.
First and foremost,
the study is based upon the self-reported sleep habits of study volunteers.
This is a notoriously subjective way of obtaining data within a study, as
participants often, consciously or subconsciously, "fudge" in their
responses based upon their reading of the question (and their perceptions of
the study's goals). In this case, the sleep-related questions in the survey
were also incidental to the primary goals of the project, and were not
designed to detect subtle variations in the volunteers' sleep cycles.
There
are many other reasons why people who sleep, on the average, less than 8
hours a night might live longer than those who sleep longer. Other factors
that may be associated with less time available to sleep (such as marital
and family responsibilities, demanding careers, more time dedicated to
recreational or exercise activities, or to reading at night before turning
in) have been linked, directly or indirectly, with a lower overall risk of
early death.
Thus, the apparent association between mild sleep deprivation
and increased longevity may have nothing to do at all with the actual number
of hours of sleep one gets each night. At the same time, chronic sleep
deprivation has been previously associated with depression, chronic fatigue,
increased interpersonal conflicts, and impaired immune response to disease.
The point of this study may be somewhat moot in the United States, however,
with recent surveys suggesting that the average American gets only about 6
hours of sleep per night anyway.
Still, the widespread publicity received
by this study is a reminder that all research papers need to be critically
evaluated before accepting the conclusions reached by their authors. In any
case, the study does suggest that mild sleep deprivation is probably not
especially harmful to one's longevity, although it sure does make me grouchy
sometimes.
Certainly, married folks who are often irritable from chronic
sleep-deprivation could find the consequences of such recurrent bouts of
grumpiness to be "less than healthful" when they are at work, or at home
with their also-harried spouses. Now there's an idea for an interesting
JWR contributor Dr. Robert A. Wascher is a senior research fellow in molecular & surgical oncology at
the John Wayne Cancer Institute in Santa Monica, CA.
Comment by clicking here.
Lowering body temperature after heart attack improves outcome
Recently, the Archives of General Psychiatry published an interesting study
suggesting that people with chronic mild sleep deprivation may live longer
than people who sleep 8 or more hours per night. More than 1 million
volunteers took an American Cancer Society survey in 1982, and were asked,
among other questions, to describe their sleep habits, sleeping pill usage,
and frequency of insomnia.
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