I definitely felt a 'first impact' which lasted for an hour or so. I think others have found the same thing, but like I said in a different post, if you're starting on an even keel and have never known 'that' feeling, a momentary jitter is nothing. For people who've experienced anxiety, the slightest sniff of it and your whole body is on red alert. I did find that taking it after a meal, before bed, helped. Taking it on an empty stomach was not pleasant! X