Sleeping too long during the day can make you more likely to get heart disease or die young, according to scientists.
In bad news for siesta lovers, researchers found that sleeping an hour or more every day can increase the risk of prematurity or illness by a third.
Afternoon sleep can be good for people who do not get much sleep at night, experts say. But the academics, from Guangzhou Medical University in China, said they should be kept short, in case chicken in the day is definitely proven to be bad for health.
The exact reason that naps can be dangerous is not certain, but past research has found that they can cause internal swelling, called inflammation, which is bad for the heart.
However, it may also be that sleep is an early sign of health problems for some people, and that they may be sleepy during the day due to threatening poor health.
Academics visited 20 studies of more than 300,000 people, their sleeping habits and their health and deaths.
Results showed that the effect was worse for women, whose risk of dying young increased by 22 percent if they took more than an hour every day.
Science about the effects of sleep on human health is obscure and there have been studies that have linked it to worse heart health, but also those who have been found to swallow during the day may reduce the risk of stroke or heart attack .
According to researchers in China who searched for medical data of more than 300,000 people (stock image), sleeping during the day can increase the risk of early death or heart disease for people who sleep for a normal period of time.
‘Daytime sleep is common all over the world and is generally considered a healthy habit,’ said Dr Zhe Pan, an author of the study.
A common view is sleep improves performance and counteracts the negative effects of “sleep debt”. Our study challenges these widespread opinions. ‘
He added: ‘If you want to take a siesta, our study indicates that it is safest to keep it under an hour.
‘For those of us not into the habit of sleeping during the day, there is no convincing evidence to begin with.’
Dr. Pan and colleagues reviewed records of 313,651 people in more than 20 previous studies, and found that four out of 10 were allowed to snap regularly.
People who napped for more than an hour each time, they found, were a third (34 percent) more likely to have heart disease, compared to non-diapers.
And the risk of dying prematurely increased by 30 percent.
However, if people slept less than six hours a night, the midday nap did not increase the risk of death or illness.
However, other studies have not linked enough sleep to other serious health problems, and adults are generally advised to get at least seven hours a night.
Dr. Pan suggested that sleep could actually be good for people who do not get enough sleep at night.
“The results suggest that shorter sleeps – especially those less than 30 to 45 minutes – can improve heart health in people who do not get enough sleep at night,” he said.
But for those who got a lot of sleep, each length of chicken the next day was found to increase the risk of going to an early grave by 19 percent.
This effect was worse for women, whose risk increased by 22 percent.
Scientists have been looking at the health effects of napping for years and studies have yielded conflicting results.
Professor Jeremy Pearson, associate medical director at the British Heart Foundation, was not involved in the research but said: ‘Whether swallowing in an overlap is good or bad for your heart has been under debate for some time.
‘Although this study suggests that daily sleeps of more than 60 minutes increase the risk of heart and circulatory diseases, more research is needed to understand why.
‘Instead of focusing on one factor, it’s important to consider a variety of lifestyle choices to keep your heart and blood vessels healthy. Doing 150 minutes of moderate exercise a week and eating a healthy Mediterranean diet can reduce your risk of heart attack or stroke.
‘Taking medication to treat high blood pressure and manage your cholesterol can also reduce your risk of life-threatening heart and circulatory diseases.’
One paper published in March this year found effects similar to those discovered by Dr Pan and the researchers from Guangzhou.
A team at Stanford University in California found that older people who regularly napped were diagnosed two-and-a-half times more often with heart disease than cancer.
The study of 11,000 people said that daytime sleepiness after a normal amount of sleep at night was associated with serious illnesses, including high blood pressure and diabetes.
Dr’s study also found this and suggested that inflammation – a type of harmful swelling in the blood vessels and soft tissues – could be the culprit.
Inflammation, which can be triggered by fatigue and exhaustion, takes extra care of the body and the immune system and can cause permanent damage if it lasts for a long time.
However, some studies have found that daytime sleepers are beneficial.
Research published by the University Hospital of Lausanne in Switzerland last year, linked sleeping twice a week to a lower risk of stroke or heart attack.
Scientists found that people who slept once or twice a week during the day were nearly 50 percent less at risk compared to those who never snoozed during the day.
But sleeping more than twice a week had no further benefits for heart care, the study found.
The team monitored an average of 3,400 people aged 35 to 75 over five years and saw 155 heart attacks as strokes. Once to twice weekly sleep was associated with almost halving the risk (48 percent) compared to those who did not sleep at all.
That study was published in Heart, a journal published by the British Medical Journal.
Dr Pan and his colleagues presented their study this week – entitled ‘The association between sleep and the risk of cardiovascular disease and mortality of all causes: a systematic review and meta-analysis of dose-response’ – at the European Society of Cardiology Congress.
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