The amount of rest you need depends on several factors that include your age, lifestyle, and health.
The general recommendations for sleep are:
Newborns: 16-18 hours a day
Preschool-aged children: 11-12 hours a day
School-aged children: At least 10 hours a day
Teens: 9-10 hours a day
Adults (including older adults): 7-8 hours a day