You’ve heard of the placebo effect, how people can get better from a fake treatment, but did you know there’s also a nocebo effect? It’s just as strong: “More than two-thirds of 34 college students developed headaches when told that a non-existent electrical current passing through their heads could produce a headache.” (From Skeptic’s Dictionary.) Alexis Madrigal did a very readable feature about it for the Atlantic called The Dark Side of the Placebo Effect: When Intense Belief Kills. I found out about it from Olivia Fox Cabane’s new book The Charisma Myth. What you don’t know can hurt you.
This is the explanation for all those people who claim cellphone radiation gives them headaches, you know.
On the other hand, remember when bees started dying en masse all over the world, and they suspected pervasive microwave radiation from cellphone towers? Turns out, it was a relatively new pesticide. What you don’t know can hurt you just fine, thank you very much.