There's nothing quite like the first days of daylight savings time to remind us that no matter how plugged in we get, how wired our homes and our lives, we've evolved in tune with the sun, moon and stars. It's hard to get up in the dark; hard to sit down to dinner while the sun is shining brightly. Near impossible, as a young child, to go to bed on a midsummer night before the sun has truly set.

On the other hand, we've gotten used to bulldozing our natural inclinations, in the service of school, work, physical fitness, TV, e-mail, etc. And the evidence is pretty clear that we're not doing a very good job helping our kids listen to their inner clocks.

The latest on the sleep front comes from KidsHealth, which just released the results of a survey of 1,187 children ages 9 to 13 across the U.S.

Turns out that an estimated 62% of kids ages 9-13 do not get enough sleep and 70% wish that they could get more sleep. Experts recommend that school-age children receive 9.5 to 10.5 hours of sleep each night. Many are barely logging 8 hours.

This doesn't just lead to kids who are unpleasant to have around. It leads to kids with lowered immune resistance to illness, kids who feel down and don't know why, kids who don't do as well as they could in school.

Another key finding: children who said their parents imposed a bedtime got an average of 45 minutes more sleep each night than those whose parents did not.

KidsHealth's advice is a good reminder that the venerable institution of bedtime is about more than giving grown-ups a kid-free hour at the end of the day, it's about safeguarding children's health.

An interesting note from research into a more extreme aspect of poor sleep: researchers have found strong evidence that a significant minority of children diagnosed with ADHD may have undiagnosed sleep disorders that can be alleviated by having their tonsils and adenoids surgically removed. As reported in the New York Times, the evidence indicates that in those cases, the ADHD symptoms can go away once the sleep disorder is eliminated.