Ah, how lovely it is to bring the generations together. At the dinner table sit my dad and his wife, freshly arrived from the East Coast for some quality time with the grandchildren. Enter a shrieking streak of a 4-year-old: my son, Drew, sobbing, screaming, clamoring for food yet refusing to eat. Try as I might to steer the conversation to the woes of airline travel, I can't get a worrisome idea out of my mind  -- my son is displaying what I'm sure will be diagnosed at our next pediatrician appointment as a solid case of hyperactivity.

"Is he tired?" asks my dad's wife, Barbara.

"He got up at five," I admit. "No nap."

Feeling  -- not for the first time since I became a mom  -- that I have some sort of head injury, I dimly remember the great paradox of sleep and children. Unlike sensible adults, who long for sleep in direct proportion to how little of it they get, exhausted children do everything they can to outwit the forces of fatigue. They accelerate. They scream. They flail and babble. They act, in fact, exactly the way Drew is acting.

As dramas go, a sleep-deprivation melt-down is spectacular to watch, particularly for out-of-town relatives, but in our house, I now realize, it's the predictable result of simple fudging on bedtime. For a couple of nights we'd sort of decided "What the heck, let him stay up a little bit later." A little bit turned into a half hour, 45 minutes, an hour. Add to this an unexpected early-morning wakening, and a little howling, laughing, crying banshee was what we had to show for it.

Watching Drew unravel made me feel like Maternalus horribilus. To make matters worse, I've since learned that doctors believe that failing to give a child enough sleep is in some ways like failing to give him enough food: It's bad for his health. According to the National Institutes of Health, a good night's sleep, along with healthy eating and exercise, is the crucial third leg in a child's health triangle.

Why it's so important
Long overlooked, lack of sleep is now considered a key contributor to children's behavior problems and physical well-being. Studies have shown that kids who don't sleep enough are inattentive, restless, irritable, and more likely to injure themselves. The American Academy of Sleep Medicine estimates that one in three kids is sleep-deprived on any given day.

Sleeping well means more than putting in the hours  -- the quality of sleep matters as well. Good sleep is uninterrupted, allowing your child to cycle through its five stages. By 6 months, a baby's sleep pattern resembles an adult's: She progresses into deeper sleep for nearly 90 minutes and then enters a lighter rapid eye movement (REM) phase, when dreaming occurs.

And our kids aren't just resting when they're off in the land of Nod. During the deeper phases of sleep, energy is restored, damaged tissue is repaired, and growth hormones are released, says Rafael Pelayo, M.D., head of the pediatric sleep service at the Lucile Packard Children's Hospital at Stanford University in Palo Alto, California.

Contributing editor Jane Meredith Adams also writes for Health and the Chicago Tribune.