Are mobile phones safe?

People today are on their mobile phones for far longer than just a couple of decades ago, which may affect their risk of cancer from such usage. — Filepic

I HAVE a very busy job that requires me to be on the phone a lot, as well as plenty of friends, whom I tend to message with throughout the day, sometimes even until 2am. I have noticed that I get tired a lot more than I used to.

My mother warned me that too much mobile phone usage can cause brain cancer. Is this true?