A study suggests extreme happiness may be bad for you. Findings: 1) "The highest levels of income, education and political participation were reported not by the most satisfied individuals, but by moderately satisfied individuals." 2) Extremely happy people "earned significantly less money" and earned lower school grades than moderately happy people. 3) They "may not live as long," either. Theories: 1) Happiness makes you complacent and kills your drive. 2) It makes you slow to adapt. 3) It makes you too optimistic and insufficiently vigilant about your health. 4) It may overstimulate your cardiovascular system. Researchers' conclusions: 1) "Happiness may need to be moderated for success." 2) "Extremely high levels of happiness might not be a desirable goal." Human Nature's conclusions: 1) Success may need to be moderated for happiness. 2) Extremely high levels of success might not be a desirable goal.