The average adult over the age of 18 needs to sleep 7 - 9 hours per night. Newborn children need 12 - 18 hours of sleep, Preschoolers need 11 - 13 hours of sleep and teenagers need to get 8.5 - 10 hours of sleep per night.
To achieve the best sleep possible you should adhere to the 3 Rs - Remove, Relax and Routine