Stanford University’s Kate Kaplan, PhD, put to rest several notions teens have about sleep at a recent event, reports the San Jose Mercury News.

Kaplan’s presentation included a fast-paced overview of some sleep physiology tenets. She said that in a typical night, a person will cycle multiple times through stages of sleep known as rapid eye movement (REM), non-REM stage 1, non-REM stage 2 and non-REM stage 3. Researchers believe that each of these stages serve different purposes, including dreaming, mood regulation, critical motor learning, growth and repair, and memory.