When I was making my appointment for the EEG tomorrow, the woman who's doing it asked me if I wore any hair products. I said "No, in fact I don't have a lot of hair, so this will be an easy one." She laughed and said that a fair number of clients have arrived wearing hair mousse. Apparently the plastics in mousse get on the scalp and cause the signal for the EEG to be degraded by about 50%.
So! Tinfoil hat wearers who fear government death rays, mind control, and the church steeples forcing you to have sexual thoughts about manhole covers! Just use lots of mousse!