Very weird that clandestine imperial gophers start to feel anxious and have trouble sleeping after a while. must be a secret laser
Pop the magnetron out of a microwave and direct it towards someone's head [0], and I imagine they're not gonna have a great time. And that's with parts available in many average homes.
The Active Denial System [1] works based on these principles, but different frequencies.
0 - Don't do this
That is why even around "small" scale radio transmitters such as phone cell towers you absolutely have to keep a safe distance, and even more around large broadcast towers or even radio amateurs doing serious satellite communication.
This is true for your skin in some cases, too: the frequencies which will quickly heat skin are a subset of the frequencies which can hurt you at high energy. For example, X-rays will do the latter a lot faster.
And that's only the considerations if you treat the skin and brain as just a hunk of stuff versus a ridiculously complex meat-computer. For an example, see the "microwave auditory effect"[0]. This effect originates inside the brain, not the ear. High levels of electromagnetic energy tends to harm even electronic computers, and they have no meat to deal with!
Ok, I'd rank it ahead of the poison theory, still behind the mass psychosis because of Hanlon though.