Congratulations in advance to those of you receiving a new e-reader from Santa Claus. But one word of advice to anyone in the nocturnal gadget habit, Christmas or otherwise: Don't take it to bed. The light will ruin your sleep.
That's the conclusion yet again of another study into the health effects of blue-spectrum light emitted by screens and by LED lighting, many of which have found that blue light keeps people awake – a troublesome enough consequence in its own right, and one that can lead to further health problems.
In this case, researchers from Harvard Medical School in the US specifically observed the sleep patterns of people reading gadgets at night versus those reading paper books.
'They found it took longer to nod off with a back-lit e-reader, which led to poorer quality sleep and being more tired the next morning,' the BBC reported. 'Blue light, the wavelength common in smartphones, tablets and LED lighting, is able to disrupt the body clock.'
Harvard locked 12 people in a sleep lab for two weeks and had them read for five days from paper books and for five days from an iPad. The research team found that the iPad individuals produced less melatonin, a hormone that fosters sleep, than did the paper book perusers.
They concluded that other e-readers including the Nook and the Kindle Fire would have the same damaging effect. (One bit of good news for Kindle lovers: The original Kindle reader does not undermine sleep because it works with reflected light rather than direct light).
Prof Charles Czeisler, the lead researcher, warned of the consequences of bad sleep.
'Sleep deficiency has been shown to increase the risk of cardiovascular disease, metabolic diseases like obesity and diabetes, and cancer,' he told the BBC. 'Thus, the melatonin suppression that we saw in this study among participants when they were reading from the light-emitting e-reader concerns us.'
Dr Victoria Revell of the University of Surrey agreed. 'We should be advising people to minimise their [light-emitting e-reader] use in the evening, particularly teenagers who are a group that are using their phones and tablets late in to the evening,' she said.
The Harvard study is not the first to link blue spectrum light to sleep deprivation.
And similar reports have prompted campaignerer like the UK's Simon Nicholas to call for reconsideration of LED streetlighting, or for use of LEDs with a lower blue quotient. One British municipality, Wigan, recently said it would use a less blue LED than originally planned, although it downplayed health concerns.
In other words, getting the blues can be miserable, but it's not always such a bad thing.
Photo is from Fabianna Ponzi via Shutterstock
A lighting health sampler on Lux:
- Light for well-being: We have a long way to go
- 'Light is a drug, so let's administer it correctly'
- Design lighting for the body not just the eyes
- And now, natural light makes nurses laugh
- Windowless workers are losing sleep
- Night time light impedes cancer drug
- Attack of the Purple People Savers: Violet lights assault hospital superbugs