You know how important good nutrition and exercise are for your health and beauty, but do you know sleep is crucial too?

When you doze you're getting more than rest. Sleep researchers say your body is healing and repairing itself. For this reason, dermatologists often suggest using your most "active" skin creams before bed. To avoid puffy, bloodshot eyes, dark under-eye circles and a pale washed-out complexion -- and for peak alertness and energy -- experts say you need eight hours of sleep a night.

Here are some tips from the Sleep Disorders Institute at New York's St. Luke's Roosevelt hospital to help you get the sleep you need:

Exercise every day. Even 20 minutes of walking can help keep stress hormones from interfering with your sleep.

Avoid large meals just before bedtime. An active digestive system can disrupt sleep.

Minimize light, noise and temperature extremes; your bedroom should be comfortably cool, about 68 degrees.

Don't read, watch television or work in bed. Use the bed only to sleep. This helps prevent you from developing sleep disorders.

Avoid caffeine, nicotine or other stimulants within four hours of bedtime.