In winter, when nights are long and the light is dim, people become depressed. There is an excess of alcohol abuse, suicides, all the collateral damage of depression. Okay, I get that.
But why, in the summer when days are long and light is bright, don't we have an excess of mania? Why aren't the streets filled with hypersexual people who haven't slept in five days? Why aren't millions of people robbing banks to finance their gambling or stocktrading habits? Why aren't airplanes being constantly hijacked, so that people can fly to the UN, or the Vatican, or the Dome of the Rock, RIGHT NOW THIS INSTANT, to proclaim their sudden, blinding insight into the Universal Brotherhood of Mankind?
Life would be a a lot more interesting if SAD were orthogonally symmetrical.