A 2020 study with nearly 800 students found a clear synchrony effect, where students performed significantly better when their class schedule matched their chronotype.

People have a genetic sleep code called their chronotype, which dictates when their brain releases hormones like melatonin, cortisol, adrenaline, and dopamine.

A study at the University of Minnesota found that high school students improved by one full letter grade when their school start times were delayed by one hour.

Chronotypes, such as early bird or night owl, are genetic and determined by the PER3 area on a person's genome.