Kids who miss out on sleep aren't just groggy in school -- they're also far more likely to do all the things that give parents nightmares.

From fistfights to fighting off depression, smoking pot to sucking back sugary drinks, researchers say kids who don't get the time they need in bed are busy doing other things… and clearly not the things you want your kids doing.

Using data from the 2007 National Youth Risk Behavior Survey, the researchers found that 69 percent of 12,100 kids between 12 and 18 years old got less than eight hours of sleep a night.

And these children -- the vast majority of kids, obviously -- were more likely to engage in some of the worst-of-the-worst activities: sex, booze, smoking, marijuana, and fistfights.

It didn't stop there, either. These kids were also more likely to battle mood problems, including sadness and depression, and even entertain serious thoughts of suicide.

Next to all that, the rest of the "risky" behaviors seem downright tame: The researchers say sleepless kids are more likely to drink a sugary soda each day, get less physical activity, and spend too much time on the computer.

Maybe it's just that kids who stay up later stay out later -- and are more likely to be in situations where they'd engage in risky activities. Or maybe it's just the fact that, at 69 percent, sleepless kids make up such a huge percentage that they're more likely to do just about anything.

Whatever the reason, as long as you keep control over what goes on in your home, make sure to set some rules about bedtime -- because even if your children aren't out boozing, smoking pot, and having sex, a lack of sleep could have an impact on everything from their waistlines to their schoolwork.

Remember, a kid may hate the rules of the house -- but those same rules will help set either a long lifetime of good habits… or a shorter span of bad ones.