Press-Republican

FYI...

August 15, 2012

How long can you live without sunlight?

Russian police have discovered 57 cult members living in an underground bunker in the Republic of Tatarstan. Many of the children ensconced in the bunker have never seen the sun, according to authorities. How long can you live without exposure to sunlight?

A normal lifespan, with the right diet. Recent research suggests that sunlight deprivation might increase susceptibility to a wide range of chronic diseases, such as diabetes and high blood pressure, as well as infectious diseases like tuberculosis and the common cold.

But it's very unlikely that an adult could die directly and exclusively from prolonged darkness. The most plausible deadly scenario is that a lack of sunlight could prevent the body from producing vitamin D, which, in turn, would inhibit calcium absorption. Very low calcium levels might lead to spasms of the larynx, causing suffocation. A proper diet, however, can easily stave off this unlikely chain of events and other health consequences, even if you live in a bunker. Vitamin D is present in egg yolks, cheese, fatty fish, and fortified milk, juice and cereal.

Children are more vulnerable than adults to vitamin D deficiency, making death from darkness somewhat more plausible.

The most obvious risk is rickets, a disease that results in malformed bones and teeth. In its extreme forms, the grisly disease can lead to other health issues like breathing irregularities and cardiovascular problems. Some pediatric researchers believe that rickets might be a factor in some cases of Sudden Infant Death Syndrome. Rickets — which may have affected up to 90 percent of children living in the cities of Europe and North America in the late 1800s — may also have played a role in measles and whooping cough outbreaks. Still, as with adults, proper diet and supplements can prevent these complications.

Living exclusively in the dark may cause some other conditions that supplements can't cure. Sunlight helps trigger the body's daily cycle of serotonin, for example. If that production cycle becomes irregular, you can suffer problems with sleep and mood.

Interest in the health-promoting effects of sunlight seems to be cyclical. In the late 19th century, when it became clear that lack of sunlight caused rickets, solar therapy became all the rage. Doctors advised patients to sunbathe, and children living at higher latitudes spent three hours per week soaking up rays in carbon or mercury arc lamps. People came to believe that the sun cured a variety of disorders, including gout, ulcers and arthritis. Patients suffering from tuberculosis spent months living in sanatoriums where sunlight was among the chief prescriptions. Around this time, tanned skin, previously associated with a life of labor and poverty, became a mark of wealth. Tanned people could afford vacations, while the poor labored in the dark recesses of factories.

Beginning in the 1930s, public health authorities began to sound the alarm about skin cancer. Over the next few decades, sunlight went from panacea to toxin, as doctors urged patients to retreat into the shade.

UV light is currently experiencing something of a medical renaissance. Studies come out weekly linking sunlight deprivation to everything from multiple sclerosis to asthma. Human skin color varies roughly according to the latitude of our ancestors' origin, and anthropologists attribute this range to our need to absorb vitamin D.

Sunlight skeptics remain, however, and it has been difficult to definitively link vitamin D to such long-term problems as diabetes and heart disease.

---

Got a question about today's news? ask-the-explainer@yahoo.com.

Explainer thanks Michael Holick of Boston University School of Medicine and Nina Jablonksi of Penn State.

Text Only | Photo Reprints
FYI...
  • asteroid-nasa.jpg White House, NASA want help hunting asteroids

    The White House and NASA on Tuesday will ask the public for help finding asteroids that potentially could slam into the Earth with catastrophic consequences.

    June 19, 2013 1 Photo

  • FACES164.jpg State photo-ID databases become troves for police

    The faces of more than 120 million people are in searchable photo databases that state officials assembled to prevent driver's-license fraud but that increasingly are used by police to identify suspects, accomplices and even innocent bystanders in a wide range of criminal investigations.

    June 18, 2013 3 Photos

  • When is a nightgown appropriate in the office?

    Who among us hasn't wondered if pajama pants are OK in the winter? What about clingy, see-through blouses for spring? And now that it's almost summer, what about nightgowns? Specifically, what about midthigh-length, straw-colored cotton nightgowns at work?

    June 17, 2013

  • doortodoor-market-box.jpg Consumers' desire for local, organic food drives online grocery business

    Just a few years ago, consumers who were fervent about eating locally-grown and organic foods had to head out to the nearest Whole Foods or farmers market. Now all it takes is a few swipes of the mouse at an online grocer like Door to Door Organics, Relay Foods or AmazonFresh.

    June 16, 2013 1 Photo

  • PARKS FOOD9.jpg National parks to offer healthier food under new standards

    The consumption of rubbery hot dogs and cellophane-wrapped sandwiches of indeterminate age is a time-honored rite of passage for generations of families making the trek to national parks around the country.

    June 15, 2013 1 Photo

  • FILM SUMMER62.jpg Predicting the summer movie sleeper hit

    Every year since, filmgoers and critics try to predict what the next "Little Miss Sunshine" will be.

    June 14, 2013 2 Photos

  • iStock_000008462647XSmall.jpg When did sunscreen get so complicated?

    Summer is almost here, which means it's time for picnics, pool parties, and every parent's favorite pastime: chasing after your kid with the sunscreen bottle. But what's arguably more arduous than slathering lotion onto a screaming 3-year-old is choosing the right sunscreen.

    June 13, 2013 1 Photo

  • cell-phone.jpg How to shield calls, chats, browsing from surveillance

    If you have followed the startling revelations about the scope of the U.S. government's surveillance efforts, you may have thought you were reading about the end of privacy. But even when faced with the most ubiquitous of modern surveillance, there are ways to keep your communications away from prying eyes.

    June 12, 2013 1 Photo

  • lifeguard.jpg Drowning doesn't look like drowning

    Drowning is not the violent, splashing call for help that most people expect. There is very little splashing, no waving, and no yelling or calls for help of any kind.

    June 11, 2013 1 Photo

  • heart.jpg 4 simple lifestyle changes can protect your heart

    According to a multi-center study led by Johns Hopkins researchers, there is a significant link between lifestyle factors and heart health, adding even more evidence in support of regular exercise, eating a Mediterranean-style diet, keeping a normal weight and -- most importantly -- not smoking.

    June 8, 2013 1 Photo