Not to be an ass, but do you have any reliable source that says drinking coffee is unhealthy?
I am a coffee drinker myself. I can imagine that it could be unhealthy, being a stimulant and all, but I really haven't seen any evidence. Coffee doesn't effect my sleep either if I don't drink any after 1-2 pm.
I'm not sure if it really effects my performance though as I grow tolerance very quickly. If I haven't drank coffee in months and then start drinking it again, I get some definite performance benefits for the first few days/weeks and then I just normalize.
I might quit again soon.