I always thought morning larks and night owls were the way they were due to habit. I started reading “Why We Sleep” by Matthew Walker and my perspective has changed. It seems that your natural circadian rhythm is something you are born with and defines your sleep habits. While everyone must be able to change their circadian rhythm to match their location, at a single location people genetically tend towards having a dip at later or earlier times. When I say dip, I am referring to a dip in body temperature and energy associated with tiredness. This is extremely unfortunate for night owls on a working schedule. The workday is biased towards morning larks. Night owls cannot fall asleep till later and are forced to wake up earlier, perpetuating a cycle of sleep deprivation.
Why would we evolve to have such variability in our circadian rhythms? Since sleep is a time of extreme vulnerability for humans, it makes sense to shorten the time when everyone is asleep. Rather than having everyone asleep for the same 8 hours, if people stagger their sleeping times, they maximize the amount of the day where someone is watching for predators. Unfortunately for night owls in the modern world, they can’t just come to work later. Perhaps it would be best for workers to have a range of hours they can come to work, say 7 am to 7 pm, and they can choose the 8 hours which they will come to work. I wonder if the increase in productivity of workers will outweigh the decrease in productivity from not having everyone there together at the same time.