Nighttime iPad use may have a negative effect on your sleep by altering levels of melatonin, according to a recent study by sleep specialists at Harvard Medical School and Brigham and Women’s Hospital.

The study consisted of 12 participants, randomly assigned to two groups. One group read printed books for four hours before bed every day for five consecutive days while the other group used iPads. After five days, the groups switched devices.

According to their findings, published in the Proceedings of the National Academy of Sciences, the researchers discovered that when participants read from an iPad, they had lower levels of melatonin and rated themselves as less sleepy an hour before bedtime.

The timing of melatonin release was also affected, delayed by more than1 1 1/2 hour when participants used an iPad compared to when they read a printed book. Using an iPad essentially shifted the sleep cycle to a later time.

Other findings in in the study:

• On average, it took iPad readers ten minutes longer to fall asleep than when they read from a printed book.
• The amount of their rapid eye movement (REM) sleep decreased but did not affect the total amount of sleep or the amount of time spent in the other non-REM sleep stages.
• iPad reported they were more sleepy and less alert the next morning than when they read a printed book.

Why?

While research of such a small group of participants should not be treated as conclusive, the findings are not without precedent as earlier studies have shown that exposure to short-wavelength light (or “blue”)–the kind produced by iPads and other types of electronic screens (TVs, computers) cause more physiological responses than long-wavelength light, the type of light the printed book readers were using.

How to have your sleep and iPad too?

There are ways of lessening the amount of blue light that is emitted from an iPad.

• Reduce the brightness of the screen
• Install an app that filters out blue light (yes, there are apps for that)
• Use an iPad screen protector (the clear plastic kind) that includes a blue light filter.

Oh, and here’s another idea if reading before sleep is a ritual you don’t want to give up: Turn out the light and listen to an audio book.

(via: Eat, Read, Sciences)