Mobile phones can affect sleeping brains - but what's it mean? Mobile phone use can affect a person's brainwaves even when the handset is switched off and the user is asleep, Australian research suggests, admitting they don't know what that means. Neuroscientist Sarah Loughran studied the brainwave patterns of 50 people in the first half hour of sleep after they had been exposed to 30 minutes of mobile phone radiation. In what is believed to be the world's largest study into mobile phone use and sleep quality, she compared those results with the brainwaves of the same people without exposure to mobile phone radiation before bed-time. "The results show that there was an increase in brainwave activity in the first part of sleep, non Rapid Eye Movement (REM) sleep, following mobile phone exposure," said Ms Loughran, a PhD student at Swinburne University's Brain Sciences Institute in Melbourne. "It was an increase in what's known as alpha brainwave activity and, at this stage, we're not entirely sure what that means. "Any adverse health consequences or effects this might have, we're not sure." Nevertheless, Ms Loughran said getting a good night's sleep did not appear to be affected by the mobile phone radiation. "We didn't find any changes in the amount of time it takes to get to sleep or the total time they slept," she said. "It didn't appear to be affecting the overall quality of the person's sleep." The participants in the study were exposed to a standard mobile phone mounted on the right side of their heads for 30 minutes before sleep. The phone was set up to transmit without them having to talk. On another night, the phone was mounted in the same way but it was not actually turned on. In what is called a double blind, crossover study, neither the study participants nor the researchers were aware of which nights the mobile phone was active and when it was not. Ms Loughran said the most interesting finding was that the effect of mobile phone radiation on brainwaves was noticeable even 30 to 40 minutes after the handset had been turned off. Her study was funded by the National Health and Medical Research Council as part of a larger investigation of mobile phone exposure in collaboration with the Australian Centre for Radiofrequency Bio-effects Research. Other research is looking at the effects of mobile phone exposure on reaction times and working memory.