There’s no clearly defined biological reason for it, and it is intuitively an evolutionary disadvantage. Sleeping during the night was extremely important for

There’s no clearly defined biological reason for it, and it is intuitively an evolutionary disadvantage. Sleeping during the night was extremely important for human survival. We evolved to find food during the day. Any waking hours at night time instead of sleeping means a huge amount of extra energy expended to support being awake. Sleep pressure has a huge evolutionary advantage. It may be a disadvantage now.