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A
new research has revealed the secret behind reducing the risk of having
a heart attack in people and you will not believe what it is.
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Scientists found people who did not
get enough sleep and stayed up too late at night had a raised pulse and
increased levels of harmful stress hormones.
Experts believe getting enough sleep, at the same time each night, allows the heart to rejuvenate.
Doctors have long warned that a lack of regular sleep raises the risk of obesity, diabetes, heart disease and even cancer.
But until now they have not been sure exactly why this is.
The new research, conducted by Northwestern University, Chicago, suggests allowing the heart to properly rejuvenate is key.
The research team believe this is strongly tied to an internal mechanism called the circadian rhythm.
Nearly all living things have this
circadian rhythm or body clock - which synchronises bodily functions to
the 24-hour pattern of the Earth’s rotation.
In humans, the clock is regulated by
the bodily senses, most importantly the way the eye perceives light and
dark and the way skin feels temperature changes.
The mechanism rules our daily rhythms,
including our sleep and waking patterns and metabolism. It also
determines if we are a ‘morning’ person or an ‘evening’ person.
There is growing evidence that
altering this rhythm - for example by working antisocial hours or
regularly traveling between different time zones - places a strain on
the body clock and creates long term health problems.
Study author Dr Daniela Grimaldi, said: ‘In
modern society, social opportunity and work demand have caused people
to become more active during late evening hours leading to a shift from
the predominantly daytime lifestyle to a more nocturnal one.
‘Our results suggest shift
workers, who are chronically exposed to circadian misalignment, might
not fully benefit from the restorative cardiovascular effects of
night-time sleep following a shift-work rotation.
‘Exposure to consecutive days of
sleep loss can impair cardiovascular function and these negative effects
might be enhanced when changes in feeding and/or sleep-wake habits lead
to a circadian disruption.’
Her team carried out a sleep deprivation experiment on 26 healthy people, aged 20 to 39.
The study participants were restricted
to five hours of sleep for eight days, with their bedtimes delayed by
8.5 hours on four of the eight days.
Their findings, published in the
journal Hypertension, found disrupting sleep patterns in this way led to
an increased heart rate.
They also found an increase in a
stress hormone called norepinephrine, which can constrict blood vessels,
raise blood pressure and expand the windpipe.
When people enter deep sleep, their heart beat is allowed to slow down - a process controlled by the vagal nerve.
But the participants in the study did not enter this state, showing reduced vagal activity and higher variability of heart beat.
Dr Grimaldi said: ‘In humans, as
in all mammals, almost all physiological and behavioural processes, in
particular the sleep-wake cycle, follow a circadian rhythm that is
regulated by an internal clock located in the brain.
‘When our sleep-wake and feeding
cycles are not in tune with the rhythms dictated by our internal clock,
circadian misalignment occurs.’
Insufficient sleep is particularly
common in shift workers, who represent 15 per cent to 30 per cent of the
working population in industrialised countries.
It follows a large British study
published in 2014 that suggested people in the UK get two hours less
sleep a night than they did 60 years ago.
The authors of that study, from
Oxford, Cambridge, Harvard, Manchester and Surrey universities, warned
that people have become ‘supremely arrogant’ by ignoring the importance
of sleep.
Professor Russell Foster, a neuroscience at the University of Oxford, said at the time: ‘We
are the supremely arrogant species; we feel we can abandon four billion
years of evolution and ignore the fact that we have evolved under a
light-dark cycle.
‘What
we do as a species, perhaps uniquely, is override the clock. And
long-term acting against the clock can lead to serious health problems.’
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