While children need more sleep than adults, how much sleep any individual needs is genetically determined. Most adults need eight hours of sleep to function at their best. Sleep until you wake on your own .without an alarm clock. That s your sleep need. You can teach yourself to sleep less, but not to need less sleep.
Sleep is as necessary to health as food and water, and rest is no substitute for sleep.
As noted above, sleep is an active process needed for health and alertness. When you don t get the sleep you need, your body builds up a sleep debt. Sooner or later, this debt must be paid with sleep. If you drive when you re sleepy, you place yourself and others at risk because drowsy drivers can fall asleep at the wheel with little or no warning. This affects when we feel sleepy and alert.