Teens typically stay up later than parents who stay up later than grandparents. And babies tend to use a 2-3 hour feed cycle which necessitates mom at the minim

Teens typically stay up later than parents who stay up later than grandparents. And babies tend to use a 2-3 hour feed cycle which necessitates mom at the minimum to be somewhat awake. There seems to be evolutionary reasons for this (probably to prevent predation). Interesting some schools and I think California in general has introduced a later start time for teens because of this biology. So it is staggered in general.