Interesting - this appears to suggest that more than 7 hours can be
counter-productive. I have found, however, that I need 8 hours, and
can see a significant difference in alertness when I get less than 8
hours of sleep.
Comments?
Udhay
http://www.medicalnewstoday.com/articles/83473.php
Too Much And Too Little Sleep Doubles Heart Death Risk
25 Sep 2007
A new UK study suggests that both too much and too little sleep can
more than double the risk of death from heart disease.
To be published in the journal SLEEP, the study is the work of
scientists from the University of Warwick and University College
London and was presented yesterday, Monday 24th September to a
meeting of the British Sleep Society.
Study author, Professor Francesco Cappuccio from the University of
Warwick's Warwick Medical School said the study involved over 10,000
civil servants from the Whitehall II Study and investigated the link
between patterns of sleep and mortality rates in the group.
The researchers looked at participants' sleep patterns during 1985 to
1988 and then again during 1992 to 1993, and monitored their
mortality rate until 2004.
They adjusted for a range of factors such as age, sex, marital
status, body mass index (BMI), smoking status, physical activity,
alcohol consumption, self rated health, blood pressure, cholesterol,
illnesses, and others.
This allowed them to see clearly what effect changes in sleep
patterns over 5 years had on rates of mortality up to 17 years later.
The results showed that participants who cut their sleeping time from
7 hours (the optimum amount recommended for an adult) to 5 hours or
less had a 1.7 increase in mortality risk from all causes, and double
the risk of death from cardiovascular causes.
Cappuccio said:
"Fewer hours sleep and greater levels of sleep disturbance have
become widespread in industrialised societies."
"This change, largely the result of sleep curtailment to create more
time for leisure and shift-work, has meant that reports of fatigue,
tiredness and excessive daytime sleepiness are more common than a few
decades ago," he added, and also said that:
"Sleep represents the daily process of physiological restitution and
recovery, and lack of sleep has far-reaching effects."
When they looked at too much sleep, Cappuccio and colleagues found a
similar effect, it also increased mortality risk.
Those participants who increased sleep duration from 7 to 8 hours a
night were more than twice as likely to die, mostly from
cardiovascular diseases, as those who did not change their sleep pattern.
Cappuccio said that while short sleep has been shown to be a risk
factor for a range of health problems such as weight gain, high blood
pressure, and type 2 diabetes, leading to higher risk of death, there
has been no similarly detailed investigation into the factors
underlying the link between long sleep and increased mortality.
He suggested however that:
"Some candidate causes for this include depression, low socioeconomic
status and cancer-related fatigue."
As far prevention is concerned however, he suggested that:
"Our findings indicate that consistently sleeping around 7 hours per
night is optimal for health and a sustained reduction may predispose
to ill-health."
Whitehall II is a prospective, longitudinal study of 10,308 men and
women working in the London offices of the British Civil Service when
enrolled in 1985.
Data collected at baseline came from clinical exams and self-report
questionnaires.
Data has been collected in eight waves since that time, with a ninth
due next month, October 2007. Whitehall II is named after an earlier
cohort, Whitehall I, that included over 18,000 male civil servants
and started in 1967.
"A prospective study of change in sleep duration; associations with
mortality in the Whitehall II cohort."
Jane E. Ferrie, Martin J. Shipley, Francesco P. Cappuccio, Eric
Brunner, Michelle A. Miller, Meena Kumari, and Michael G. Marmot.
To be published in SLEEP.
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((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
