My mom gave me her "usual" nighttime dose one time because I was in pain and couldn't sleep. I was on another planet for a few hours and it was scary. I generally do a tincture and measure it in drops. It was also Maine stuff and not the crap you get in NH.

For me I do get the racing heart even with lower amounts and I get a bit dizzy but I know that's when I need to put my head down and sleep. I can imagine it could be, at the very least, uncomfortable if you aren't aware you have taken anything.