Pulling together the latest research, scientists are proposing a new theory that much of ADHD may, in fact, be a problem associated with a lack of regular circadian sleep.
“There is extensive research showing that people with ADHD also tend to exhibit sleep problems,” said Dr. Sandra Kooij, an associate professor of psychiatry at VU University Medical Centre in Amsterdam and founder of the European Network Adult ADHD, who presented the theory at the 2017 European College of Neuropsychopharmacology Conference.
She said what the scientists are doing 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,” she said.
She said the researchers believe this because both day and night rhythm is disturbed, as well as the timing of several physical processes, including sleep, temperature, movement patterns, timing of meals, and more.
“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 said.
Kooij noted that in 75 percent of ADHD patients, the physiological sleep phase — where people show the physiological signs associated with sleep, such as changes in the level of the sleep hormone melatonin, and changes in sleep-related movement — is delayed by 1.5 hours.
Core body temperature changes associated with sleep are also delayed, reflecting melatonin changes, she said.
Additionally, many sleep-related disorders are associated with ADHD, including restless-leg syndrome, sleep apnea, and the circadian rhythm disturbance called delayed sleep phase syndrome.
“ADHD people often show greater alertness in the evening, which is the opposite of what is found in the general population,” she continued.
Many sufferers benefit from taking melatonin in the evening or bright light therapy in the morning, which can help reset the circadian rhythm, she said.
Recent research also has shown that around 70 percent of adult ADHD sufferers show an oversensitivity of the eyes to light, leading many to wear sunglasses for long periods during the day, which may reinforce the problems associated with a circadian shift.
Lastly, chronic late sleep leads to a chronic sleep debt, associated with obesity, diabetes, cardiovascular disease, and cancer. This cascade of negative health consequences may be preventable by resetting the sleep rhythm, she said.
“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,” Kooij said. “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,” she said.
“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.”.