A new study suggests that people
who sleep 8 hours or more a night, or less than 4 hours, have a slightly
higher risk of dying in a given time period than those who get 6 and 7
hours of shut-eye.
However, the researchers note
that they can't be sure why some of the study subjects had longer or shorter
sleep periods, and there's no evidence that sleep patterns-or changing
them-can truly influence mortality risk.
Some sleep experts, including
those at the National Sleep Foundation (NSF), agree.
Although the study reports
data that is of interest, limitations in the study methodology restrict
the conclusions that can be reached, particularly about the amount of
sleep needed to sustain an individual's health, safety and well-being.
In the study researchers examined
the findings of a previously conducted study that included, among other
things, data on the sleep habits of 1.1
million people men and women between the ages of 30 and 102.
The study subjects, friends
and family members of American Cancer Society volunteers, were interviewed
in 1982 about diet, exercise, sleep and health problems and then followed
up 6 years later.
Participants who reported sleeping
8 or more hours or less than 4 or 5 hours a night experienced a slightly
higher chance of dying-at least a 15%
increase in risk -- within that time compared with those who
slept 7 hours a night.
Interestingly, only one in
a thousand slept at the lower end of the time scale.
Furthermore, the researchers report that insomnia was not associated with
excess mortality, although the use of a prescription sleeping pill was
also associated with a slightly increased risk of dying during the six-year
The study does seem to indicate
that fewer than 8 hours of shuteye a night are not necessarily detrimental
The study was not designed
to answer why sleeping longer may be deleterious or whether people could
extend their life spans by sleeping less. It is possible that people who
sleep longer tend to suffer from sleep apnea, a condition in which impaired
breathing puts stress on the heart and brain. The need for sleep is akin
to the need for food, in that getting less than people want may be better
While agreeing that the risk
of dying from reduced sleep is low, he added, "It's hard to know
if we shouldn't be worried about five hours of sleep -- if you are talking
about being able to drive a truck a thousand miles the next day, being
able to concentrate, make important decisions, that's a whole other story."
The average American sleeps
7 hours on weekdays, according to the 2001 Sleep in America Poll (conducted
by the National Sleep Foundation). The new study shows that it is quite
safe to sleep five, six, or seven hours a night, and people who sleep
less than eight hours do not need to worry.
The study's findings may lead
the public to be less concerned about insomnia -- a sometimes serious
condition marked by an inability to sleep. Even mild sleep deprivation
is associated with increased daytime sleepiness, which may lead to adverse
outcomes, such as accidents.
Insomnia is associated with
impaired quality of life, functional impairment, physical symptoms, and
coronary heart disease. Sleep is not bad for you and insomnia is not good.
Sleeplessness produces health
consequences that were not measured in the study. The amount of sleep
you get impacts how alert you are, your risk for accidents, how you perform
at work and school. There's much more to life than how long you live.
The National Sleep Foundation
emphasizes that substantial research serves as the basis for the recommendation
that adults obtain an average of seven to nine hours of sleep each night.
The group notes that individuals
will require different amounts of sleep and that if someone sleeps 8.5
hours a night and feels alert and energetic, it would be incorrect to
reduce sleep time based on the study.
Archives of General Psychiatry
February 15, 2002;59:131-136