J.D. Moyer decided recently to conduct a little experiment with artificial light and his sleep cycle.

The sleep-deprived Oakland, California, resident had read that strong light -- whether it's beaming down from the sun or up from the screens of personal electronics -- can reset a person's internal sleep clock.

So, for one month, whenever the sun set, he turned off all the gadgets and lights in his house -- from the bulb hidden in his refrigerator to his laptop computer.

It worked. Instead of falling asleep at midnight, Moyer's head was hitting the pillow as early as 9 p.m. He felt so well-rested during the test, he said, that friends remarked on his unexpected morning perkiness.

"I had the experience, a number of times, just feeling kind of unreasonably happy for no reason. And it was the sleep," he said. "Sure, you can get by with six or seven hours, but sleeping eight or nine hours -- it's a different state of mind."

Moyer may be onto something.

More than ever, consumer electronics -- particularly laptops, smartphones and Apple's new iPad -- are shining bright light into our eyes until just moments before we doze off.

Now there's growing concern that these glowing gadgets may actually fool our brains into thinking it's daytime. Exposure can disturb sleep patterns and exacerbate insomnia, some sleep researchers said in interviews.

"Potentially, yes, if you're using [the iPad or a laptop] close to bedtime ... that light can be sufficiently stimulating to the brain to make it more awake and delay your ability to sleep," said Phyllis Zee, a neuroscience professor at Northwestern University and director of the school's Center for Sleep & Circadian Biology.

"And I think more importantly, it could also be sufficient to affect your circadian rhythm. This is the clock in your brain that determines when you sleep and when you wake up."

Such concerns are not entirely new: One sleep researcher said Thomas Edison created these problems when he invented the light bulb. But they've been revived by the popularity of Apple's new slate computer, the iPad, which many consumers say is good for reading at night in bed, when the brain thinks the environment should be dark.

Unlike paper books or e-book readers like the Amazon Kindle, which does not emit its own light, the iPad's screen shines light directly into the reader's eyes from a relatively close distance.

That makes the iPad and laptops more likely to disrupt sleep patterns than, say, a television sitting across the bedroom or a lamp that illuminates a paper book, both of which shoot far less light straight into the eye, researchers said.

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