There's a correlation between being a early bird and having lots of outcomes. It's not just income, it's like happiness and productivity. There are times in the 24 hour period that it's advantageous to be aroused,. awake, vigilant, looking for food or mating opportunities. i think we can say there is a tendency for early birds to get the worm but we don't know whether it's because the worms are laid out for them on a buffet early, or whether they tend to be different kinds of people.