Seriously, I recall hearing about some sort of study which claimed that depressed people were more accurate in their predictions about the future than non-depressed people. Being right didn’t make the depressed people less depressed. Perhaps depression is simply a malfunction in an organism’s naturally occuring bias toward optimism. If a person (or a coyote or a manatee or a mole rat) is realistic rather than optimistic, surely that interferes with his or her chances of reproducing.

As for false happiness. I hate to use the term because I despise it as much as you may, but ignorance is bliss. The person that is happy under false pretenses is still happy. Now if you mean that false happiness means they are acting like they are happy when they aren’t. That is another thing.. that person is not optimistic by any means. (notice i did not use the term that refers to a static way of being)