(NBC NEWS) -- New mother Angelique Millette makes putting a baby to sleep look easy.
She should. She's an expert and teaches other parents about good sleep habits.
"When babies don't get enough sleep, it starts to impact their behavior. It disorganizes them," Millette explains.
New research confirms Angelique is right.
A study of more than 10,000 children in the United Kingdom links irregular bedtimes with behavior problems.
Kids who did not have a consistent bedtime from an early age through childhood were more likely to misbehave by time the time they were 7 years old.
Those behavior problems were not diagnosed by doctors, but by those who know kids best: Teachers and mothers.
"Most parents know just from looking at their children, they know when they're sleepy and not sleepy based on their behavior," says the Children's Healthcare of Atlanta Sleep Center's Dr. Gary Montgomery
While the study does not prove irregular bedtimes cause bad behavior, the researchers found the problem can be reversed.
When kids got back on track with a regular bedtime, their mood and behavior improved.
"The child gets a lot of satisfaction and security from that predictability each night," Dr. Montgomery explains.
Sleep experts recommend evening reading and warn nighttime is not the time for TV or texting.
"Part of making sleep changes or using a sleep solution is a little bit about setting a limit and being consistent with that limit and that's not always easy to do," Millette says.
In the current study parents and teachers completed a questionnaire that assessed children's behaviors including hyperactivity, conduct problems and problems with friends.