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 sleeping from seven hours a night to five or less faced a 1.7-fold
increased risk in mortality from all causes and more than double the
risk of cardiovascular death.
The findings highlight a danger in busy modern lifestyles,”A
third of the population of the UK and over 40 percent in the U.S.
regularly sleep less than five hours a night, so it is not a trivial
problem,” he said in a telephone interview.
“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 U.S. funding, is the
first to link duration of sleep and mortality rates.
The study looked at sleep patterns of participants aged 35-55 years
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 sleeping to
more than nine hours.
In this case, however, there was no cardiovascular link and 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.”
