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.
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.
It is useful to be aware of new health research regarding cell phone usage and cell phone radiation. The first cell phone call was made in 1985 and that phone cost $5,000 and weighed about 9 pounds. The change in size, weight and cost of devices today has probably led to over 50% of the human race owning a mobile device, the fastest growing technology on the planet.