Fact: A midday nap reverses information overload—those feelings of irritation, frustration and declining performance on mental tasks that set in during intense encounters with new information.

Fact: The late stage of sleep—sometimes missed by early risers—can boost by 20% your acquisition of coordination crucial for playing a sport, a musical instrument, or any fine motor control.

Fact: Sleep strengthens the nerve circuits that underlie learning and memory, allowing the brain to make and consolidate new neural connections.

Fact: Missing out on sleep seriously impairs the body's ability to process blood sugar, impeding the action of insulin much as in diabetes. Sleep deprivation may be an important contributor to obesity. It also elevates the stress hormone cortisol.

Fact: Sleeping for six hours a night may sound pretty good, but it's not likely enough to keep your immune system happy. Restricting your sleep by a mere two hours a night for one week provokes the process of inflammation, which may set people up for heart disease.

Fact: Sleep deprivation curtails your ability to come up with creative solutions to life's challenges.

No doubt you know by now that sleep doesn't just put the brain on hold while you lay in bed. Your brain is very active during sleep. Sleep organizes the memories of habits, actions, and skills learned during the day. Sleep gives you the mental energy to master complex tasks and the ability to concentrate.

In other words, success comes not only from what you accomplish when you are awake. We also get power from the ability of body and mind to consolidate themselves during the night.

Sleep is so important that your brain remembers how much of it you get. And it compensates for sleep loss by allowing you to fall asleep faster and staying asleep longer the next night.

Sacrifice sleep and you sacrifice peak performance. It's noticeable in rates of traffic accidents and work injuries.

The trouble is, modern life is eating away at your sleep. There's too much to do, and too little time to do it in. So we give up sleep. More and more, we are sleeping less and less, and building up a sleep debt in the process.

The trouble is, say experts, society may have changed since the introduction of the light bulb eroded the natural cycles of day and night to which our energy levels are tuned. But our bodies have not.

There's no one set amount of sleep that's best for everyone. People vary greatly in their need for sleep. Still, surveys by the National Sleep Foundation report that most adults get less sleep than they need. On average, adults sleep seven hours a night during the workweek. Only 35% of adults sleep eight hours or more per night; 36% sleep 6.5 hours or less. Most people compensate by sleeping longer on weekends, a switch guaranteed to keep your body clock confused.

The price we pay for cheating sleep is steep: short-changing the brain of learning potential, short-circuiting your moods, and dimming your alertness, maybe even making you gain weight and compromising your health. Coffee can keep you going for a while. But nothing can compensate for sleep. Your body needs it and your brain needs it.

Cornell psychologist James B. Maas, Ph.D., qualifies as one of the nation's leading sleep advocates. In his book Power Sleep (HarperCollins), he implores us to sleep not necessarily more but more efficiently, so we can always perform at our best. Here are his Golden Rules of sleep.

1. Get an adequate amount of sleep every night. Identify the amount of sleep you need to be fully alert all day long and get that amount every night. It will dramatically change your mood and your ability to think critically and creatively. For some people, six hours a night may be adequate. One or two in a hundred can get by on five hours. Many others will need as much as nine or 10 hours. Whatever the amount, most people need 60 to 90 minutes more sleep than they presently get.
2. Establish a regular sleep schedule. Go to bed every night at the same time and wake up without an alarm clock at the same time every morning—including weekends. Within six weeks the hours you spend in bed will begin to synchronize with the sleepy phase of your biological clock. Your mood will be the winner.
3. Get continuous sleep. For sleep to be rejuvenating you should get your required amount of sleep in one continuous block.
4. Make up for lost sleep as soon as possible, even though you cannot replace lost sleep all at once. And when you sleep longer to catch up, try to do so by going to bed earlier than usual. Otherwise your normal waking time will shift and you're unlikely to get to sleep at the usual time the following night.

Sweet dreams.