Less than six or more than 10 hours sleep a night raises people’s risk of heart disease

Eight hours sleep may really be the ideal amount, new research suggests. 

Getting less than six, or more than 10, hours of shut a eye a night makes people more likely to develop high blood pressure and cholesterol, as well as excessive weight around their midriffs, a study found today.

Known as metabolic syndrome, these symptoms increase the risk of heart disease, stroke and type 2 diabetes.

Previous research suggests both insufficient and excessive sleep causes inflammation in the body, which is linked to metabolic symptoms.

Too much or too little sleep may raise people’s risk of heart disease and stroke (stock)


Insomnia may be psychological, research suggested in May 2017. 

Sufferers who take placebo pills feel more rested than those who get no treatment at all, according to a review of 13 studies.

According to the researchers, the simple act of taking a pill may ease the anxiety that makes it harder for some insomnia sufferers to fall asleep.

Dr Patrick Finan from Johns Hopkins University, who was not involved in the study, said: ‘Insomnia is shaped by expectation and perception, so it is not surprising that placebos, which implicitly alter expectation, are effective in improving perceptions of sleep.’

The researchers, from the University of Sydney, examined data from a total of 566 insomnia sufferers who were assigned to either receive a placebo that they believed was an active treatment or no pills at all.

Placebo patients reported greater improvements in their ability to fall asleep, the total amount of rest they got and their sleep quality.

Comparing placebo against recognised insomnia therapies can give inaccurate results as simply believing you are receiving a sleep-inducing treatment can ease the condition.

Study author Dr Ben Colagiuri, said: ‘The comparison with no treatment means that we can be sure that the improvement we observed was due to a genuine placebo effect, rather than being an artifact of simply taking part in a trial.’

Insomnia may be considered a condition of the mind due to one person averaging four hours sleep a night and feeling sufficiently rested, while another may get seven hours and feel the amount or quality of their shut eye is inadequate, Dr Finan explained.

How the research was carried out 

The researchers, from Seoul National University, analysed 133,608 people aged between 40 and 69 years old.

The participants’ were asked how long they spent asleep, on average, each day in the past year, including daytime naps.

Blood, DNA and urine samples were also collected.

The participants were considered to have metabolic syndrome if they had at least three of the following: a large waist, high blood sugar levels, low levels of ‘good’ cholesterol and high blood pressure. 

Metabolic syndrome is defined as a cluster of ingredients that together increase people’s risk of heart disease, stroke and type 2 diabetes.  

The findings were published in the journal BMC Public Health. 

Aim for seven to seven-and-a-half hours sleep 

This comes after a study released in May 2017 suggested sleeping for more or less than seven or seven-and-a-half hours a night increases people’s risk of lung cancer and dementia.

Too little, or excessive, shut eye is thought to disrupt people’s ‘sleep hormone’, which drives tumour growth, according to the researchers.

Lack of sleep is also associated with elevated copper levels in the blood, which further increases cancer’s risk, they added.

Being disturbed from nightly slumbers raises people’s dementia risk by one-and-a-half times, the study by the University of Eastern Finland found.

This may be due to an accumulation of a specific protein that reduces the size of the region of the brain associated with memory and prevents brain cell regeneration, the researcher said.

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