A natural periodic state of rest for the mind and body, in which the eyes usually close and consciousness is completely or partially lost, so that there is a decrease in bodily movement and responsiveness to external stimuli. During sleep the brain in humans and other mammals undergoes a characteristic cycle of brain-wave activity that includes intervals of dreaming.
According to the American Academy of Sleep Medicine:
- Infants 4 to 12 months should sleep 12 to 16 hours per 24 hours (including naps) on a regular basis to promote optimal health.
- Children 1 to 2 years of age should sleep 11 to 14 hours per 24 hours (including naps) on a regular basis to promote optimal health.
- Children 3 to 5 years of age should sleep 10 to 13 hours per 24 hours (including naps) on a regular basis to promote optimal health.
- Children 6 to 12 years of age should sleep 9 to 12 hours per 24 hours on a regular basis to promote optimal health.
- Teenagers 13 to 18 years of age should sleep 8 to 10 hours per 24 hours on a regular basis to promote optimal health.
- Younger adults (18-25): should sleep 7-9 hours
- Adults (26-64) should sleep 7-9 hours
- Older adults (65+) should sleep 7-8 hours
