Little sleep ups diabetes risk

2012-04-17 07:58

Washington – Increased numbers of workers pull the night shift. Teenagers text past midnight and stumble to class at dawn. Travellers pack cheaper overnight flights.

Nodding off behind the wheel is not the only threat from a lack of sleep. Evidence is growing that people who regularly sleep too little and at the wrong time suffer long-lasting consequences that a nap will not cure: increased risk of diabetes, heart disease and other health problems.

“We have a societal conspiracy for sleep deprivation,” says Russell Sanna of Harvard Medical School’s sleep medicine division, who attended a Tedmed conference last week where scientists called sleep loss one of health care’s big challenges.

Just how unhealthy is it? Consider how sleep may play a role in the nation’s diabetes epidemic.

Studies have long shown that people who sleep fewer than five hours a night have an increased risk of developing Type 2 diabetes, the kind that tends to strike later in life.

Rotating shift work, three or more night shifts a month interspersed with day or evening hours, raises the risk, too, says a recent report from researchers who analysed years of medical records from the huge Nurses’ Health Study.

Diet and physical activity are big factors in Type 2 diabetes. Certainly it is harder to work out or choose an apple over a doughnut when you’re tired, especially at 3am when your body’s internal clock knows you should be sleeping.

A study published last week, however, shows sleep plays a more complex role than that.

As sleep drops and normal biological rhythms are disrupted, a person’s body physically changes in ways that can help set the stage for diabetes, reports neuroscientist Orfeu Buxton of Boston’s Brigham and Women’s Hospital.

Buxton’s team had 21 healthy volunteers spend almost six weeks living in a laboratory where their diet, physical activity, sleep and even the light was strictly controlled.

The volunteers started out well-rested. But for three of those weeks, they were allowed only about 5½ hours of sleep every 24 hours – at varying times of the day or night, to mimic a bad shift rotation or prolonged jet lag.

That knocked out of whack the body’s “circadian rhythm”, a master biological clock that regulates such patterns as when a person becomes sleepy or how body temperature rises and falls.

What happened was startling: Blood sugar levels increased after meals, sometimes to pre-diabetic levels, because the pancreas stopped secreting enough insulin, Buxton reported in the journal Science Translational Medicine.

At the same time, the volunteers’ metabolic rate slowed by 8%. The researchers had them on a diet so they did not gain weight, but Buxton says typically, a metabolism drop of that size could mean gaining 4.5 kilograms to 5.5 kilograms over a year.

The results make sense, says Dr Michael Thorpy, sleep centre director at New York’s Montefiore Medical Center and a neurology professor at Albert Einstein College of Medicine.

“If we’re going to spend a third of our day sleeping, there’s got to be a good reason for it,” says Thorpy, who notes that diabetes is far from the only worry.

Up to 70 million Americans are estimated to suffer from chronic problems with sleep, from insomnia to sleep apnoea.

Impaired sleep has been linked to high blood pressure, heart disease, obesity, depression, memory impairment and a weakened immune system.

Still another concern: The World Health Organisation has classified night shift work as a probable carcinogen, because too much light at night may hamper a hormone involved both with sleep and suppressing tumour cells.

Don’t people adjust to the night shift if they are on it long enough?

Buxton says rotating shifts probably are most worrisome. In his study, the volunteers’ bodies went back to normal after nine nights of sufficient sleep at the right time.

No one knows how long it takes before sleep deprivation and an off-kilter biological clock may cause permanent damage.

Montefiore’s Thorpy says natural night owls seem to adapt better to night shifts, but that people never fully adapt if they swing back to daytime schedules on their days off.

Also, about 30% of regular night workers have trouble sleeping during their off hours or are particularly fatigued, he says, something termed “shift work disorder”.

The consumer message:
» The National Institutes of Health says adults need between seven and nine hours of sleep daily for good health.

» People who work nights should go straight to bed when they get home, Buxton advises. Avoid too much light along the way.

Thorpy says wearing yellow- or orange-tinted sunglasses on the drive home can block short-wavelength “blue light” that triggers wakefulness.

» Let natural light help keep the biological sleep clock on schedule, advises Harvard’s sleep-education website. For most people, sunlight in the morning is crucial. For the night shift, more bright light in the evening shifts people’s internal clock, Buxton explains.

» For anyone, a sleep-inducing bedroom is one that’s dark, quiet and cool.

Avoid caffeine, alcohol and stressful situations near bedtime. Electronics right before bed aren’t advised, either. Going to bed and waking up at the same time every day also helps.

Join the conversation! encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions. publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
Comments have been closed for this article.

Inside News24

Traffic Alerts
There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.