A new study reports that the rate of ADHD diagnosis among children has increased over the last decade.

The study involved an analysis of medical records from a major health plan in Southern California. Records for more than 842,000 children were analyzed. Trends from 2001 to 2010 were examined.

Results show that the rate of ADHD diagnosis was 2.5 percent in 2001. The diagnosis rate increased to 3.1 percent in 2010. This represents an increase of 24 percent.

The study was published online ahead of print Jan. 21.  It appears in the journal JAMA Pediatrics.

A strength of this study is that it relied on the clinical diagnosis of ADHD. Previous studies relied primarily on parental reports, notes the CDC.

But parental reports also show a similar trend. Parent-reported ADHD diagnosis increased 22 percent from 2003 to 2007. It rose from 7.8 percent to 9.5 percent.

One drawback of the current study is that it focused only on Southern California. The CDC reports that ADHD rates vary by state. The rate of parent-reported ADHD diagnosis is lowest in Nevada at 5.6 percent. California also is on the lower end at 6.2 percent. In contrast, North Carolina has the highest rate of 15.6 percent.

Why is the diagnosis rate for ADHD on the rise? A WebMD report notes that the increase may be related to growing awareness of ADHD. Parents, teachers and doctors have all become more aware of the problem.

Parents also should be aware of the complex link between sleep and ADHD. Sleep problems are common in children with attention-deficit/hyperactivity disorder. Children with ADHD may resist going to bed and struggle to fall asleep. The quality of their sleep also may be poor.

Sleep loss also can cause ADHD-like symptoms. Children tend to respond to sleep loss in a different way than adults. Sleep-deprived adults may be sleepy and sluggish during the day.

But tired children tend to be hyperactive. Sleepy children also are more likely to be impulsive, inattentive and disruptive. These behaviors are key symptoms of ADHD.

Children with a sleep disorder that disrupts their sleep also may be hyperactive during the day. Common sleep problems in children include sleep apnea and restless legs syndrome.

The AASM recommends that school-aged children get at least 10 hours of sleep per night. Younger children need ever more sleep. Get help for your child’s sleep problem at a local sleep center.