Toddlers should get 11-14 hour of sleep. Naps count as part of this calculation.
3-5 year olds should get 11-13 hours of sleep. Naps count as part of this calculation.
6-13 year olds should get 9-11 hours of sleep. This is not common. Bedtime should be quite early with an early school schedule.
Teens should be getting 8-10 hours of sleep. Sleep is directly connected to memory. When my oldest was at college trying to memorize hours of classical music for her Senior piano recital, we found scientific research saying that the best strategy for increasing your memory was to get a good night’s sleep. Whether you are 5 or 25 or even 85, sleep makes a big difference.