Prolonged cell-phone use before bedtime may impair your sleep quality. In a study of 71 people, participants took longer to reach deep sleep and had shorter bouts of deep sleep after they had been exposed to cell-phone radiation for three hours, compared with having been exposed to sham signals for the same amount of time.

The effect was too subtle for the subjects to perceive a difference in their sleep (though they did report more headaches), but “deep sleep is the most important aspect of sleep for recharging your energy reserves,” says Bengt Arnetz, a professor of occupational and environmental health at Wayne State University in Detroit.

“If you have problems sleeping, use a wireless or hands-free device to keep the radio-frequency fields away from the head,” Arnetz suggests. [source: Allure]