My sister once told me that a customer who was taking antidepressants was experiencing weird little shocks in her brain, with twitching and head pain. The head pharmacist where she worked said that the "zaps" were a common side effect of that type of antidepressant.
And there are people who fight tooth and nail just to get a prescription to these things!?
Yeah, I get those when I miss a dosage. It's horrible. I find myself unable to focus on anything, even simple conversations or chores around the house, until the symptoms have been relieved.