By comparison, even a very powerful high-end Wi-Fi router only produces around 1 watt of microwave energy and, unlike the magnetron in a microwave oven, a Wi-Fi router radiates that minuscule 1 watt of power in a bubble-like-cloud around the router. In other words, if you wanted to heat up even a milliliter of water above room temperature using this energy, you’d be waiting…well, forever.
Another thing, a WiFi router is not continuously sending data, when devices don’t communicate to the internet. In an idle situation, a WiFi router just sends beacon signal, like “Hello I’m a WiFi router” every x miliseconds and your smartphone just listen to it, like a radio. The same is for GSM/3G/4G. Your mobile is not communicating to the GSM antenna continuously, otherwise it would drain your battery in minutes and your mobile gets very hot. Further more, the government forced the mobile companies to lower the transmit power, that’s why you see more GSM antennas (actually called basestations) in places like cities for better coverage.
According to a peer-reviewed Nov. 2008 study in the journal Epidemiology, exposure to cell phone radiation while in the womb "was associated with behavior difficulties such as emotional and hyperactivity problems around the age of school entry."  A Dec. 2010 study replicated those findings.  A peer-reviewed Mar. 15, 2012 study found that mice exposed to cell phone radiation in the womb "were hyperactive and had impaired memory" as adults. 
An analysis of data from NCI's Surveillance, Epidemiology, and End Results (SEER) Program evaluated trends in cancer incidence in the United States. This analysis found no increase in the incidence of brain or other central nervous system cancers between 1992 and 2006, despite the dramatic increase in cell phone use in this country during that time (22).
We have essentially no control over whether we live or die -- except that we should avoid dangerous behaviors like smoking, becoming obese, not wearing seat belts, texting while driving, etc. Otherwise, over a trillion cells carry on countless biochemical processes that we have no control over. One out of four people will get cancer. Beyond avoiding foolish behavior, we can't influence that risk.
✅ PROTECT YOUR HEAD & BODY FROM RADIATION: It is scientifically proven that it’s best to keep your phone away from your body because the radiation exposure often exceeds FCC regulations. That’s why our emf protection cell phone radiation shield will immediately negate symptoms such as headaches, dizziness, memory loss, anxiety, fatigue and much more.
This article is not correct. Wifi waves are just a low frequency sound wave. Everyone is having a placebo effect, or doing the equivalence of listening to music using ear buds all night by having the router too close to their heads. This article was made to play on your fears and to have you buy products like iPad radiation shields and other junk. This article is harmful to people.
But meanwhile know for certain that research is confirming that exposure to ICRW or Information Carrying Radio Waves, also called wireless energy, can do all kinds of things from compromising immunity and causing the body to react by forming tumors to creating symptoms like headaches, trouble sleeping, anxiety and ringing in the ears. Other common sources of this same type of "non-ionizing radiation" include: cell phones, baby monitors, and computers and Smart Meters. Studies of symptoms from exposure to RF microwave(yes this EMF energy goes by many titles!) include heart racing, tingling sensations, numbness, dizziness, and fatigue.
Studies by five independent research groups regarding cell phones and brain tumors have revealed significantly increased risks of a benign tumour of the cranial nerve supplying the ear. This grows slowly and must be removed in a major operation that can result in permanent facial paralysis. Other risks found were cancer of the glial cells (including neurons) of the nervous system and cancer of the meninges, the membrane covering the brain and spinal cord.