What is a healthy sleep?

Healthy sleep can be explained from three aspects: sleep quantity, sleep quality and optimal sleep time. Sleep amount: children 10 hour, adults 7 hours. The quality of sleep requires falling asleep within half an hour, basically not waking up for one night or one time, having no dreams or less dreams, sleeping deeply and not being awakened or disturbed. The best sleep time is 10 from night to 6: 00 am, and children from 8: 00 pm to 6: 00 am.