Yes I get brain zaps as well when I'm just about to fall asleep. They're annoying and somewhat freaky, but I've gotten somewhat used to them and I don't panic over them anymore. They usually happen for about a week after I've taken a hallucinogen, or sometimes because of uppers.
A friend of mine who doesn't do drugs, but is on ritalin for ADD, gets them as well, sometimes when he's merely just 'zoning out' while daydreaming.