Eli5: what cause people to be either heavy sleepers or light sleepers?

Question

Eli5: what cause people to be either heavy sleepers or light sleepers?

In: Biology

Answer 1

imma guess it
-eli5: People get tired after day of work and playing so they sleep but some people doesn’t like waking up
-adv: its about how much of their brain is working on its sensory organs and their level of tiredness, trust to the environment and mostly genetics