(Relaxnews)—In a study of more than 500 people, those who used technology before bedtime reported higher levels of stress than those who didn't, LiveScience reports on May 29. But the association wasn't found with all forms of technology: emailing or watching television before bed wasn't linked with greater stress. Other non-stressful pre-bed activities? Reading a book and exercising. In the study, researcher Israel Arevalo, a former psychology student at University of Texas-Pan American, recruited 500 subjects ages 18 to 73 who completed an online survey, LiveScience reports. The study was presented this weekend at the annual meeting of the Association for Psychological Science. A separate study published in the journal Nature last week found that night-time exposure to LED rays illuminating from tablets, computers, TVs, and smartphones can disrupt your body's natural rhythms, and raise your risk for not only sleep loss but health problems.