I made the mistake of taking it at 3pm the first day - couldn't sleep! I'm being a little cautious because I experienced my heart beating very - loud is the only way I can describe it, it wasn't palpitations but it was kind of like I'd been doing exercise or something, the next time I took it I had a splitting headache BUT - I think these symptoms may have been caused by a lot of detoxifying stuff that I've recently added to my diet, trying to clear candida. It may well have been die off. So I'm proceeding but with caution - I'll post any more results I have.