Teenagers require 9 ¼ hours of sleep, but only 8% of US high school students get that much. This occurs because of both intrinsic factors (ex. circadian rhythm and how it’s affected by light) and external factors (school start times, studying, extracurricular activities.) In middle school and high school, teenagers require the same amount of sleep, but because of these factors, high schoolers get less sleep during the weekdays. Sleep deprivation makes it harder to function throughout the day and makes teens more susceptible to mental disorders such as depression and anxiety.