the reason you feel sadder at night is because your body has literally run out of the chemicals for regulating your emotions and maintaining a happy mood
so i don't buy this and the reason i don't buy this is that it doesn't happen at parties. at a good party you get happier as the night goes on, not sadder. i think the real reason is that we're supposed to be surrounded by our tribe at night and often aren't, except at parties twitter.com/sadalsvvd/stat…