People who do not get enough sleep are more than twice as likely
to die of heart disease, according to a large British study
released Monday.
Although the reasons are unclear, researchers said lack of sleep
appeared to be linked to increased blood pressure, which is known
to raise the risk of heart attacks and stroke.
A 17-year analysis of 10,000 government workers showed those who
cut their sleep from seven hours a night to five or less faced a
1.7-fold increased risk of death from all causes and more than
double the risk of cardiovascular death.
The findings highlight a danger in busy modern lifestyles,
Francesco Cappuccio, professor of cardiovascular medicine at the
University of Warwick's medical school, told the annual conference
of the British Sleep Society in Cambridge.
"A third of the population of the UK and over 40 percent in the
US regularly sleep less than five hours a night, so it is not a
trivial problem," he told reporters.
"The current pressures in society to cut out sleep, in order to
squeeze in more, may not be a good idea - particularly if you go
below five hours."
Previous research has highlighted the potential health risks of
shift work and disrupted sleep. But the study by Cappuccio and
colleagues, which was supported by British government and US
funding, is the first to link duration of sleep and mortality
rates.
The study looked at sleep patterns of participants aged 35-55 at
two points in their lives - 1985-88 and 1992-93 - and then tracked
their mortality rates until 2004.
The results were adjusted to take account of other possible risk
factors such as initial age, sex, smoking and alcohol consumption,
body mass index, blood pressure and cholesterol.
The correlation with cardiovascular risk in those who slept less
in the 1990s than in the 1980s was clear but, curiously, there was
also a higher mortality rate in people who increased their sleep to
more than nine hours.
In this case, however, there was no cardiovascular link and
Cappuccio said it was possible that longer sleeping could be
related to other health problems such as depression or
cancer-related fatigue.
"In terms of prevention, our findings indicate that consistently
sleeping around seven hours per night is optimal for health," he
said.
(Agencies via China Daily September 26, 2007)