S & T

Updated: May 23, 2013 03:38 IST

LEDs disrupt sleep

N. Gopal Raj
Comment (5)   ·   print   ·   T  T  
A LED-based signal installed on Anna salai in Chennai... Photo: M. Moorthy
The Hindu
A LED-based signal installed on Anna salai in Chennai... Photo: M. Moorthy

In the frenetic, coffee-fuelled lives of today, too many people are not getting enough sleep. Modern light-emitting diodes (LEDs) used in energy-efficient lighting as well as television and computer screens, laptops, tablets and various handheld devices, are adding to the problem, according to an article appearing today (May 23) in Nature.

Lack of sleep takes its toll. “The cumulative effects of sleep loss and sleep disorders have been associated with a wide range of deleterious health consequences including an increased risk of hypertension, diabetes, obesity, depression, heart attack and stroke,” noted a 2006 report from the U.S. Institute of Medicine.

The electric light has had a powerful impact on the body’s clock, known as the circadian rhythm. “And light affects our circadian rhythms more powerfully than any drug,” remarked Charles A. Czeisler in his perspective article in Nature’s Outlook feature on sleep. He is a sleep specialist with Harvard Medical School and Brigham and Women’s Hospital at Boston in the U.S.

Apart from rods and cones needed for vision, the eye’s retina also contains ‘intrinsically photosensitive retinal ganglion cells’ (ipRGCs). These light-sensitive cells help synchronise the body’s circadian rhythm to the natural day and night cycle.

When artificial light strikes those cells, the body gets misled and responds by promoting wakefulness and inhibiting sleep.

Consequently, “many people are still checking e-mail, doing homework or watching TV at midnight, with hardly a clue that it is the middle of the solar night,” observed Dr. Czeisler. “Technology has effectively decoupled us from the natural 24-hour day to which our bodies evolved, driving us to go to bed later. And we use caffeine in the morning to rise as early as we ever did, putting the squeeze on sleep.”

White light emitted by LEDs was typically rich in blue light. This mattered because ipRGCs were most sensitive to blue and blue-green light. So night-time exposure to LEDs was typically more disruptive to circadian rhythms and sleep than the old incandescent light bulbs.

Since solid-state light fixtures could carry multicoloured LEDs, it would be relatively easy to control their light intensity and colour composition. “The adverse effects of night-time light on sleep and circadian rhythms can be reduced by replacing blue-enriched light with red- or orange-enriched white light after sunset,” he suggested.

In addition, “it is critical to establish a regular bedtime and wake time,” said Dr. Czeisler in an email. The interval between those two times must allow a person to catch enough sleep. An average adult needed eight hours of sleep. Children needed more sleep. A typical high school student would need more than nine hours in bed.

“Children become hyperactive rather than sleepy when they don’t get enough sleep, and have difficulty focusing attention, so sleep deficiency may be mistaken for attention-deficit hyperactivity disorder (ADHD), an increasingly common condition now diagnosed in 19 per cent of U.S. boys of high-school age,” he pointed out in the article.

Very informative and though provoking article. Many thanks to to the Author. The ill effects of laptop/desktop screen use at night are equally disastrous, be it LED or LCD. I found a small software programme called f.lux (easily available via google search) quite helpful. This software works with sunrise/sunset times at your location and converts the bluish light of screens in to more sombre Amber light. This is exactly what the author has mentioned it in this article. We have been trying this for a some time and it works beautifully. However, nothing like using a power button to put your device to sleep at least an hour before you do :)

from:  Akshay
Posted on: May 24, 2013 at 17:59 IST

Perhaps, the high intensity of LED screens may be a culprit behind
stated syndrome than the LED lighting itself. In normal incandescent
or fluorescent lighting, the light scattered uniformly in all
directions; but this may not be the case of LEDs which emits in narrow
solid angles due to their specific designs. This gives a non-uniform
intensity distribution of light, which creates irritations and related
biological complications.
This work may direct future LED technologies in modifying their
designs as well as implementation of special optics to yield uniform
In view of earlier comment of angela alvares, I would like to clarify
here is that the scientific works like this are based on strict
conditions such as similar biological schedules, diets, health, age
groups, genders, etc, and so it is unwise to doubt the credibility of
present results.

from:  D.S.Atul
Posted on: May 24, 2013 at 12:25 IST

The life time of LEDs is manifold longer than the incandescent bulbs. One of the intial business cartels of capitalism in the early 90s was the 'Light Bulb conspiracy'. The light bulb invented by Edison had a life time of 25,000 hours. But such a bulb is not good for the market. So an agreement was signed by the bulb makers to make bulb that lasts not longer than 1000 hours. Engineered to be obsolete. And people's mind tuned to change for new things. Else the economy won't grow. LEDs doesn't support this economic model!!
A cooked up research?

from:  Sivakumar
Posted on: May 23, 2013 at 18:46 IST

Best is to use daylight as much as possible. I use warm glow (sunset overtones) in my
LED lights and am on the computer and other electronics for the major part of the
evening but I've rarely had a problem falling asleep at night so I think the above
article is somewhat exaggerated. Sleep problems occur from dwelling on stressful
situations, or focusing on modern day artificial or deceitful avenues for success or
simply as some would say, having a guilty conscience. Put in a full day of work in
whatever you are meant to do or what makes you truly happy, be truthful in all your
dealings and you are more likely to fall asleep with healthy exhaustion at the end of
the day...and don't forget a healthy diet and some exercise!

from:  angela alvares
Posted on: May 23, 2013 at 18:40 IST

A much needed article in today's sick world!

from:  Vishwas
Posted on: May 23, 2013 at 14:14 IST
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