Having trouble getting to sleep? It could be your iPad, Kindle or any other screen you use for reading before turning the lights out. New research explains why this happens, but what can you do about it — short of going back to paper?|
The Lighting Research Center at the Rensselaer Polytechnic Institute recently published a study explaining how readers' beloved tablets and e-readers keep people up at night. A dark room triggers the body's production of melatonin, a hormone that acts as a messenger telling the body it's time to sleep, and lighted screens interfere with that message.
Any light can make it tough to fall asleep, but light of shorter wavelengths, such as the bluish tints emitted from LED-backlit screens, suppresses nocturnal melatonin, according to the sleep study. The brighter the light and longer the exposure, the more difficult it can be to fall asleep.
The findings come just after Amazon introduced its new Kindle PaperWhite e-readers, which offer higher-contrast, lighted displays, an answer to Barnes & Nobles' popular Nook with GlowLight. And multi-purpose tablets, such as the iPad, Google Nexus 7 and the newest high-resolution tablets recently launched by Barnes and Noble, are frequently used as e-book readers.
But more vivid screens aren't necessarily better when it comes to sleep.
"The ones that do not emit light should be better (for sleeping)," said Mariana Figueiro, director of the Lighting Research Center's Light and Health Program.
She offered some tips for getting a better night's sleep without giving up your e-reader or tablet. Figueiro recommends reducing the brightness of the screen to its minimum (which helps conserve battery life, too). Tablet users can go into "settings" to do this.
Kindle and Nook e-readers that lack a built-in light don't allow users to adjust the screen, but because the device's e-ink displays have lower contrast, these e-readers are less disruptive to sleep.
However, Kindle Paperwhites and Nook with GlowLight should be dimmed as much as possible, Figueiro said.
Readers also should reduce the amount of time spent using the device before bedtime. "One hour exposure is not so bad," she said. "But after two hours, we saw significant melatonin suppression."
The same holds true for any lighted screen, including TVs and computers. Turn your devices off at least one hour before you plan on turning off your light and going to sleep.
In addition to reducing disruptive light, you can make other adjustments to your display that will make it easier to sleep. Most devices give users some text and display-color options for reading. For instance, in iBooks for the iPad, tapping the font icon at the top right corner of a page displays a number of adjustments for nighttime reading.
Here, readers can dim the screen and choose the night theme, which shows white type on a black field, the configuration Figueiro said was best for nighttime reading. E-readers and Kindle or Nook apps used on a laptop or other device offer the same white-on-black scheme.
Despite what your mom probably told you as a kid ("Read in bright light or you'll go blind"), reading in lower light isn't harmful, and will make falling asleep easier.
"Low-level illumination, equivalent to a nightlight, for example, is OK with a tablet," Figueiro said.
You should also hold your device as far away from your eyes as possible — and comfortable — to reduce the amount of light reaching the eyes. Enlarge the font size if necessary, a feature that all e-readers, tablets and reading apps offer.
If you're still having trouble falling asleep, it may not be your device.
"All of these will help minimize melatonin suppression, but one can still be active and alert because of the task," she said. "So we cannot blame it all on the light coming from the screen."
Note to readers: The new Nook HD tablets come in two sizes: a 7-inch device starting at $199 and a 9-inch model starting at $269. They are available for pre-order now, but won't ship until Nov. 1. My editor tried them out at a Barnes & Noble launch event in New York City and said the new Nooks "are more than just Kindle clones."
However, we're counting on an iPad Mini in October. While this hasn't been confirmed by Apple, we've already seen accessories for them. If you're planning to buy a tablet, let's wait and see what Apple has in store before jumping on a tablet from Amazon, B&N or Google — the new iPad Mini could be competitively priced.
Ogden, Utah-based TopTenREVIEWS.com guides consumers by comparing products in the world of technology, including electronics, software and Web services. Have a question? Email Leslie Meredith at firstname.lastname@example.org, or join her at AskLeslie on Facebook or Leslie Meredith on Google+.
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