Preschoolers: 4 and 5 year olds need about 10 to 12 hours
School age children and preteens: 6 to 12 years need about 10 hours
Teenagers need about 8 to 10 hours of sleep per night, requiring more sleep as their activity during the day increases.
Sleep is important to fight illness, deep sleep is important for learning as your dream sleep is for memory consolidation of what you have learned during the day. Not enough sleep can lead to sleep deprivation and sleep debt that accumulates. Napping prevents or creates problems getting to sleep that night which contributes to sleep deprivation and debt. Sleep debt needs to be made up on the weekend to avoid accumulation. Daytime sleepiness can create hyperactivity, problems learning, short term memory deficits and poor sustained attention.