Less than 6 or more than 9 hours of sleep a night bad for your health: study

By Mark Waghorn via SWNS

Sleeping less than six hours a night - or more than nine - is bad for your health, according to new research.

Too much or too little rest raises the risk of an infection by 44 and 27 percent respectively, say scientists.

Those with chronic insomnia are also more likely to need treatment with antibiotics, according to the findings.

The first analysis of its kind is based on almost 2,000 Norwegians visiting doctors' surgeries.

Corresponding author Dr. Ingeborg Forthun, of the University of Bergen, said: "Most previous observational studies have looked at the association between sleep and infection in a sample of the general population.

"We wanted to assess this association among patients in primary care, where we know that the prevalence of sleep problems is much higher than in the population at large."

The results, published in the journal Frontiers in Psychiatry, are consistent with the idea around seven hours of shut-eye is optimal.

Forthun said: "The higher risk of reporting an infection among patients who reported short or long sleep duration is not that surprising as we know having an infection can cause both poor sleep and sleepiness.

"But the higher risk of an infection among those with a chronic insomnia disorder indicate that the direction of this relationship also goes in the other direction - poor sleep can make your more susceptible to an infection."

Participants were handed short questionnaires asking about sleep quality and recent infections.

Evidence linking the two already exists. A previous study found people deliberately infected with the virus that causes the common cold were less likely to develop symptoms if they slept well.

It offers hope of cutting down on antibiotic use. Resistance to the drugs could claim ten million lives a year by 2050 - one of the biggest threats facing mankind.

Sleep disturbances are avoidable. Treatments include cognitive behavioral therapy, supplements, exercise, reducing noise and light and eating at the right times.

The volunteers were asked how long they typically sleep, how well they feel they sleep and when they prefer to sleep — as well as whether they had had any infections or used any antibiotics in the past three months.

The survey also contained a scale identifying cases of chronic insomnia disorder.

Risk of infection raised by a quarter or more among those who failed to get the right amount.

The unique project design allowed for the collection of data from a large group experiencing real-world conditions.

Forthun said: "We don’t know why the patients visited their GPs. It could be an underlying health problem affects both the risk of poor sleep and risk of infection. But we don't think this can fully explain our results."

She added: "Insomnia is very common among patients in primary care but found to be under recognized by general practitioners.

"Increased awareness of the importance of sleep, not only for general wellbeing but for patients' health, is needed both among patients and general practitioners."

Sleep is also known to play an important role in mental and cognitive health. It has also been found to protect against a heart attack or stroke.

One study found those who slept less than six hours or more than seven had a higher chance of death due to cardiac causes.

They had more toxic proteins that can trigger high blood pressure and hardening of the arteries.