California card?

I've had, what I consider to be, moderate insomnia (e.g. I try to go to bed at 10pm, and I'm still awake at 1am). I have been smoking marijuana for over a year now and have come to find that smoking a little bit before bed basically knocks me out and I get a great deep sleep and wake up fresh and recharged the next day.

I'd like to get SOMETHING (a "card", "doctors note", whatever) that allows me to smoke marijuana. I've heard the "doctors notes" have no legal bearing, and ultimately comes down to if the cop is a nice guy or not. I've also heard there are "state cards" and "county cards".

My ideal situation: Something that can legally protect me on the state-level, and not be on my record.. or at least VERY minimally. I have a very successful future and don't need this coming back to bite me in the ass when I'm older. I mean yeah, its a medicine, but not everyone sees it like that.