Does Wi-Fi pose a health risk?

AccUser writes: "Like many Slashdotters, I have a Wi-Fi network at home. Recently, I had to relocate my office from our spare room to our bedroom, and due to the thickness of the walls in our house (slate built, circa 1880) it was necessary to move my wireless router into the bedroom too. All three computers are switched off at night as they are in the bedroom, but the servers in the loft continue to run and access the Wi-Fi network sporadically. My wife has complained of sleepless nights since the relocation, but she is not aware that the wireless router has moved too. The other night though, I left a laptop downloading a couple of ISO images (9GBs over 512Kb/s ADSL, so will take 36 hours or so) and we both had interrupted sleep, headaches, and malaise. I have looked for information regarding health issues related to Wi-Fi signals and equipment, and most authorities suggest that the risks are negligible at most, although very little evidence is given in support. Does Wi-Fi present any health risks? Should I just invest in some tin-foil nightcaps?"