Lack of sleep in kids linked to ADHD symptoms

Most parents don't need a study to tell them that too-little sleep can lead to behavior problems the following day. In my experience, late nights generally mean ill-tempered mornings—and not just for the kids.

But the occasional late night aside, what if a child is routinely short on sleep? They may be at higher risk of behavior problems related to ADHD (attention deficit hyperactivity disorder), according to a new study.

The study included 280 healthy 7- and 8-year-olds in Finland. Parents recorded their bedtime and wakeup time for seven days and noted any factors that might have affected their sleep, such as travel or illness. And for an objective measurement of sleep time, the children wore a device on their wrist called an actigraph, which logs sleep duration by recording movement.

Parents also filled out standard questionnaires that explored their child's sleep habits and rated their level of ADHD symptoms, such as being hyperactive, impulsive, or inattentive. Each child was then given a score for each of these symptoms and an overall ADHD symptom score.

The researchers found that children who averaged less than 7.7 hours of sleep a night had higher levels of hyperactivity and impulsivity than those who slept more. They also scored higher on the overall ADHD symptom scale, although their inattention score wasn't elevated. When researchers factored in other things that could have affected these results (such as certain conditions and sleep problems), they still found that kids getting less than 7.7 hours had higher levels of hyperactivity and impulsivity, although their overall score wasn't raised.

The difference in symptom scores between short and longer sleepers wasn't huge, but it was significant, with scores steadily increasing as sleep time decreased. Even so, the study wasn't set up to show cause and effect, and can't say whether short sleep actually caused ADHD symptoms—or, perhaps, whether ADHD symptoms led to less sleep. The study also didn't report whether any of the kids had actually been diagnosed with ADHD.

What you need to know. Scientists are still unraveling why our bodies need sleep, and what happens when we don't get enough. But research does show that nearly 1 in 3 children in the United States are lacking pillow time. And poor sleep has been linked to subpar performance in school, and to depression, obesity, and other health problems. So although the connection between sleep and ADHD needs more research, there are still plenty of other reasons to make sure your kids are getting enough shuteye. For me, a cheerful morning is reason enough.

—Sophie Ramsey, patient editor, BMJ Group

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