s-n-s, good luck with the lasik.
i concur with gb. valium isn't a big deal (which is why it's so dangerous because of addiction. it's too easy to feel good at first, but i digress).
like gb said, it just kind of mellows you out. not like the crappy, kinda out-of-it way you do from things like antihistamines, or anesthesia. just like nothing bothers you, all's well, nappy nappy time.
before you go testing it, call your doc and talk to him/her about it. tell them your concerns, and see if they think a "test" would be a good idea.
generally, they prescribe a specific drug and dosage and expect you to follow orders, no monkeying around. unless they say it's ok to take more or less.
talk to them before you try anything, ok?
A true lover of nature does not despair now that his mistress has turned a colder cheek.