How Much Do Sleep Problems Underlie ADHD Symptoms?
Researchers investigate a chicken-and-egg question.
Years ago, after I had given a presentation about ADHD to a group of health care professionals, an audience member wanted to make a comment. “You know that ADHD is really just people who don’t sleep well,” she said. I told her at the time that poor sleep can definitely make things worse but no, actually I hadn’t heard that, and would love to see the study that suggested this.
I never heard from her, but more than a decade later came across this recent study that did try to sort out these issues by doing cognitive attention tasks and EEGs among a group of 81 adults diagnosed with ADHD and 30 controls.
Subjects were brought into the lab and given a number of computer attention tasks while observers rated their level of sleepiness. They also filled out rating scales regarding their ADHD symptoms and underwent EEG testing, as previous work has demonstrated that wave slowing in the frontal lobes can be associated with both EEG and sleepiness.
Most of the comparisons for the study were done between the ADHD and control group but for some analyses, the authors reshuffled participants into 3 different groups: ADHD subjects and controls who were rated as being at least slightly sleepy during the testing (the sleepy group); ADHD subjects who were not sleepy; and control subjects who were not sleepy.
Overall, the authors found many adults with ADHD didn’t sleep that well and were rated as sleepier than controls during the attention tasks. Perhaps more importantly, however, the association between sleepiness and poorer cognitive performance remained significant even after controlling for levels of ADHD symptoms. In other words, some of their attention problems evident in these tasks seemed to be related to their sleepiness and not any intrinsic concentration problem. Interestingly, however, the major EEG deviations such as frontal lobe “slowing” were found to be most related to ADHD status, although also showed some associations with sleepiness.
The authors concluded that many of the cognitive deficits associated directly with ADHD may actually be due to on-task sleepiness. They write that “daytime sleepiness plays a major role in cognitive functioning of adults with ADHD.”
The study has some important implications. While clinicians have long been aware that sleeping problems are quite common among those diagnosed with ADHD, the degree to which these difficulties are responsible for attention problems is often underappreciated. These data suggest that if we can help people with ADHD “just” sleep better, their symptoms might improve.
But that is sometimes easier said than done. In the child and adolescent psychiatry clinic where I work, we try to be cautious about all medications, including those for ADHD. If we hear about sleep problems (and we often do from parents who understandably can get quite frustrated with them), we try to address them, and this study ads support for that approach. Sometimes, it involves making recommendations about children getting more exercise or not playing video games late into the night. Sometimes, it involves teaching families about sleep hygiene – practices that can promote longer and more restful sleeping. But frequently sleep remains tough to correct and then the question becomes whether or not to use medications for sleep, which can have side effects just like ADHD medications. Nevertheless, this study reminds us clinicians not to ignore sleep problems among those who struggle to regulate their attention.
It is also important to mention what this study doesn’t say, which is that the whole idea of ADHD can be chalked up to sleepiness. Most of the study’s subjects did not have significant sleep problems and were not classified as “sleepy” when observed. Further, the EEG testing showed that some of the slowing patterns were more indicative of having an ADHD diagnosis than being sleep deprived, a finding that the authors did not expect. Indeed, the researchers devoted several paragraphs to the possibility that the origin of some individuals’ ADHD symptoms may come from deficient oxygen supply before or after birth. This may help connect the dots between previous research that has linked ADHD with low birth weight and maternal smoking during pregnancy.
Returning to the comment at my lecture years ago, my questioner definitely had a point, and we shouldn’t downplay the role that poor sleep may have in making people who already struggle to stay focused even worse. At the same time, we see once again how oversimplified dismissals of ADHD come up short under scrutiny.
David Rettew, M.D., is a child psychiatrist at the University of Vermont and author of Child Temperament: New Thinking about the Boundary between Traits and Illness.