Could attention deficit hyperactivity disorder (ADHD) be associated with a lack of regular circadian sleep? At the 30th annual European College of Neuropsychopharmacology (ECNP) Congress in early September in Paris, France, researchers presented the hypothesis that ADHD and sleep problems, experienced by roughly 75% of people with ADHD, may not be separate issues.
“There is extensive research showing that people with ADHD also tend to exhibit sleep problems. What we are doing here is taking this association to the next logical step: pulling all the work together leads us to say that, based on existing evidence, it looks very much like ADHD and circadian problems are intertwined in the majority of patients,” said Sandra Kooij, MD, PhD, associate professor of psychiatry, VU University Medical Centre, Amsterdam, and founder and chair of the European Network Adult ADHD
“We believe this 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. If you review the evidence, it looks more and more like ADHD and sleeplessness are two sides of the same physiological and mental coin,” she added.
At the conference, Dr. Kooij presented the findings that are the basis for this possible association:
- In a full 75% of ADHD patients, the physiological sleep phase is delayed by 1.5. hours.
- In these patients, core body temperature changes associated with sleep are also delayed, which reflect changes in melatonin.
- Many sleep-related disorders are associated with ADHD, including restless leg syndrome, sleep apnea, and circadian rhythm disturbance.
- People with ADHD are often more alert in the evening, generally opposite of what is seen in the general population.
- People with ADHD can benefit from taking melatonin in the evening, or from bright light therapy in the morning. These may help reset their circadian rhythm.
- Studies have shown that roughly 70% of adult ADHD sufferers have an ocular hypersensitivity to light, and may wear sunglasses for long periods during the day, only to reinforce circadian shift problems.
“We are working to confirm this physical-mental relationship by finding biomarkers, such as vitamin D levels, blood glucose, cortisol levels, 24-hour blood pressure, heart rate variability, and so on. If the connection is confirmed, it raises the intriguing question: does ADHD cause sleeplessness, or does sleeplessness cause ADHD? If the latter, then we may be able to treat some ADHD by non-pharmacological methods, such as changing light or sleep patterns, and prevent the negative impact of chronic sleep loss on health,” said Dr. Kooij.
“We don’t say that all ADHD problems are associated with these circadian patterns, but it looks increasingly likely that this is an important element,” she concluded.
In commenting on this, Professor Andreas Reif, University Hospital, Frankfurt, and leader of the EU CoCA project on ADHD, and who was not involved in the research, said “A disturbance of the circadian system may indeed be a core mechanism in ADHD, which could also link ADHD to other mental illnesses such as depression or bipolar disorder. But also beyond these pathophysiological considerations, sleep problems and abnormalities of circadian rhythms are a huge problem for many patients, heavily impacting on their social life.”
“More research into the interconnections between ADHD and the ‘inner clock’ is thus very relevant to improve patients’ lives and to shed light on the disease mechanism of ADHD,” he concluded.