In ADHD news, a growing body of research is turning the way some experts think about the condition on its head, suggesting that many cases of Attention Deficit Hyperactive Disorder may simply be rooted in a lack of regular circadian sleep.

“There is extensive research showing that people with ADHD also tend to exhibit sleep problems,” said Sandra Kooij, an associate professor of psychiatry at VU University Medical Centre, Amsterdam, at the recent European College of Neuropsychopharmacology Conference in Paris. “We believe this is because the day and night rhythm is disturbed, the timing of several physical processes is disturbed, not only of sleep, but also of temperature, movement patterns, timing of meals, and so on.”

Kooij focused on the 75% of people with ADHD whose physiological progression to sleep — markedly, the release of the sleep hormone melatonin — is delayed by 1.5 hours. This delay, she explained, has a domino effect, throwing off the entire day that follows; body temperature, movement and hunger are disturbed or delayed, which can lead to inattention and disruptive behavior. However, many sufferers benefit from taking melatonin in the evening, or undergoing bright light therapy in the morning, treatments that reset circadian rhythm to a schedule that allows for a fuller night of sleep.

“If you review the evidence, it looks more and more like ADHD and sleeplessness are two sides of the same physiological and mental coin,” Kooij said.

Other research supports the theory, particularly for children with ADHD. Per the Washington Post:

Karen Bonuck, a professor of family and social medicine at Albert Einstein College of Medicine in New York, is known for her work on a 2012 study of 11,000 children published in the journal Pediatrics. It found that those with snoring, mouth breathing or apnea (in which a person’s breathing is interrupted during sleep) were 40 percent to 100 percent more likely than those without the sleep issues to have behaviors resembling ADHD by age 7.

“There’s a lot of evidence that sleep is a big factor in behavior in children,” Bonuck said in a recent interview.

In an age when more and more children aren’t getting the full amount of sleep they need for healthy growth (often more than parents realize), Kooij’s theory seems believable — which just means more research is needed; as Kooij herself noted, the link between sleep problems and ADHD is clear, but its nature isn’t: “Does ADHD cause sleeplessness, or does sleeplessness cause ADHD?” she said.

If the latter, treatment for ADHD, which now tends to rely on long-acting stimulants that help people focus (and may, Kooij posited, be contributing to off-set sleep cycles by lasting too long), could shift to more natural interventions to address the underlying sleep problems. While Kooij and colleagues stopped short of linking all ADHD cases to lack of sleep, she laid out a plan for future research into the biomarkers of sleep that would confirm whether lack of sleep is indeed the cause of ADHD.