Our studies point that WIFI is not completely safe at home near the animal or human body because it employ harmful radio waves. But it is safer compared to cellphone that it is close to our brain during communications. WIFI signals are everywhere. If you switched off your WiFi at night, you are still exposed to the WIFI signals coming in from neighbors but we have a significant reduction of the bioeffects of WIFI with distance from the router. Future investigations will focus on the long term bioeffects of WIFI placed at an important distance from the animal or the human.
The Federal Communications Commission (FCC),  US Government Accountability Office (GAO),  and the US Food and Drug Administration (FDA),  have all concluded that there is no evidence in the scientific literature proving that cell phones cause brain tumors or other health problems. According to the FDA, "attempts to replicate and confirm the few studies that did show a connection [between cell phone radiation and head tumors] have failed." 
Joel Moskowitz (@berkeleyprc) of the University of California, Berkeley School of Public Health, US, says: “This is the largest technological experiment in the history of our species, with potential health risks we still know next to nothing about.” This view is shared by Denis Henshaw, professor of human radiation effects at Bristol University, UK, who said: “Vast numbers of people are using cell phones and this could be a time bomb of health problems.”