Three out of four kids drink caffeine every day, and the more they drink, the less sleep they're likely to get, according to a new study.

The results showed children ages 5 to 7 drank an average of 52 milligrams of caffeine a day, equivalent to the amount in a can of caffeinated soda. And kids of this age slept an average of 9.46 hours a night, longer than what the Centers for Disease Control and Prevention recommends.

However, kids ages 8 to 12 took in twice as much caffeine — an average of 109 milligrams a day, equivalent to nearly three cans of caffeinated soda. And kids in this age group slept an average of 8.47 hours per night, which is below the levels recommended by the CDC.

The finding shows that the amount of sleep that kids get seems to be affected by their drinking an average of one to three cans of soda a day, the researchers said. Many studies have shown the effects of caffeine in adults, but little research has been done on caffeine's effect on children.

William J. Warzak, a psychology professor at University of Nebraska Medical Center, and his colleagues surveyed the parents of 200 children ages 5 to 12 about their kids' snack and beverage consumption habits.

Warzak said the researchers were surprised to find that caffeine consumption wasn't linked to bed-wetting, even though the substance is a known diuretic.

"Conventional wisdom is to curtail caffeine consumption by children who wet the bed, especially in the evening," Warzak told MyHealthNewsDaily.

Warzak noted that the children who drank the most caffeine in the study didn't suffer from insomnia; they simply slept less than the others.

Past studies have shown that caffeine has effects on children's health. A study published this month in the journal Experimental and Clinical Psychopharmacology showed that caffeine raises boys' blood pressure.

A study in the same journal found that highly caffeinated drinks can slow people’s reaction times.

Now Warzak is doing a similar study to measure the effects of caffeine in a bigger group of kids.

The study was published today (Dec. 16) in the Journal of Pediatrics.

Pass it on: Seventy-five percent of kids consume caffeine every day, and the more caffeine they drink, the fewer hours they sleep.

Follow MyHealthNewsDaily staff writer Amanda Chan on Twitter @AmandaLChan.

This article was provided by MyHealthNewsDaily, a sister site to LiveScience.