Want a Good Night's Sleep? Ditch the E-Reader.

If you can't sleep, there are a few home-style remedies, including warm milk, soothing music and the touchstone: reading, preferably something on the duller side.

But even the most boring book, if read on an electronic device, can make it considerably more difficult to doze off, according to a new study published in the Proceedings of the National Academy of Sciences.

Sleep experts have long speculated that the glow emitted from our various screens has a profound effect on our body's circadian clock (the system that regulates sleep), and previous research has shown that blue light, used by many backlit devices, suppresses melatonin. This small but important study goes one step further, illustrating the profound impact e-readers have on the way we sleep.

Related: How Much Sleep Do You Really Need?

In the study, 12 participants spent two weeks at a sleep laboratory in Boston; for five nights, they were instructed to read on an iPad for four hours before a 10 p.m. enforced bedtime, and for five nights they read from a paperback instead. Their sleep was then monitored, with researchers tracking how long it took each participant to fall asleep as well as how long he or she spent in each stage of the sleep cycle. Finally, blood samples were collected so participants' melatonin levels could be measured.

Grim news for e-reader enthusiasts: Reading on an iPad delayed participants' circadian rhythm by more than an hour, making them less sleepy before bed and sleepier and less alert the next morning. What's more, it shortened the length of REM sleep (often called dream sleep).

Related: Your Brain Likes Plain Old Paper More Than It Likes E-Readers

Although the study only used iPads, the researchers examined other popular e-readers and devices (including Kindle Fire, Nook Color, smartphones and laptops) and found they emit a similar blue light, meaning the impact would be more-or-less the same.

These findings are admittedly not great for tech companies hawking various e-reading devices, but there's a silver lining for Amazon: While newer models of the Kindle come with their own light-source, the company's original Kindle doesn't, and therefore is a safe-bet for before-bed reading.

For the rest of us, the study is an important reminder that screen-time right before bed – even if we're just reading! – isn't recommended. As it is, we're a chronically sleep-deprived nation, and apparently, our new-fangled devices are contributing to the problem.

Related: New E-Reader App Hatches a Clever Plan to Get You to Actually Read