Are cell phones a health hazard?

Is there any health hazard caused by sleeping with your phone near head?

Apart from discomfort if you lie on it, or disrupted sleep if it rings, no, at least as far as is known right now. Concerns about the possible effects of electomagnetic fields have not been substantiated conclusively through research so far.

That said, there is a growing body of research suggesting electromagnetic exposure from a variety of sources is a contributor to the development of some illnesses, including cancer, and the World Health Organization has issued a fact sheet advising people that there is a basis for concern which is being more rigorously investigated.

These scientific papers provide more information:

This article originally appeared as my answer to a question on Quora.