Most healthy 45-year-old women do best with 7–9 hours of sleep each night, with small adjustments based on health, hormones, stress, and daily load.

Most 40-year-old women do best with 7 to 9 hours of sleep a night, with many feeling well on around 7½ to 8 hours of steady, good-quality rest.

Most 15-year-old boys need 8–10 hours of sleep each night to stay healthy, learn well, and handle daily stress.

Most 35-year-olds do best with 7 to 9 hours of nightly sleep, with 7 to 8 hours working well for many.

A typical 16-year-old boy needs about 8 to 10 hours of sleep each night to stay healthy, learn well, and feel steady during the day.

A typical 12-year-old girl needs about 9–12 hours of sleep each night, with most tweens doing best around 9½ to 10 hours on school days.

A 12-year-old boy usually needs 9 to 12 hours of sleep each night to stay healthy, learn well, and handle daily life.

A 14-year-old girl usually needs 8 to 10 hours of sleep each night to stay healthy, learn well, and feel balanced.

Most 13-year-olds need 8–10 hours of sleep each night to stay alert, learn well, and keep mood and health on a steady track.

An 11-year-old usually needs 9 to 12 hours of sleep each night to stay healthy, learn well, and handle busy days.