AsianScientist (Feb. 19, 2025) – As many as half of all kids diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) struggle to sleep. ADHD is a neurodevelopmental condition, which impacts the ability to focus, sit still and practice impulse control. While scientists have suspected that an out-of-sync circadian rhythm might play a role, the precise biological connection between ADHD and sleep has been unclear.
In a new study, researchers from Hamamatsu University in Japan, in collaboration with international institutions, have discovered that genetic traits which lower the nighttime release of melatonin—a hormone essential for coordinating the sleep-wake cycle—are associated with more severe ADHD symptoms. Published in Psychiatry Research Communications, their finding suggests that improving sleep habits could be a new avenue for managing ADHD symptoms in children.
The brain produces its peak melatonin levels in response to darkness after nightfall. While melatonin doesn’t directly cause drowsiness, it plays a key role in signaling the body to wind down before bed.
To check for a potential genetic link between melatonin secretion and ADHD, the researchers compared the data from two large studies: one focusing on the genetic basis of ADHD and the other on melatonin production. Their analysis revealed that genetic variations tied to lower melatonin levels were also associated with ADHD.
Next, the team explored how these shared genetic traits translate in individual cases by examining the data from the Hamamatsu Birth Cohort for Mothers and Children, a comprehensive long-term study tracking children’s development from birth. This dataset, which included records of ADHD symptoms, sleep behaviour and genetic profiles of eight- to nine-year olds, showed that children genetically predisposed to reduced melatonin production experienced more pronounced ADHD symptoms, particularly difficulties with inattention.
To trace the molecular pathways mediating this phenomenon, the researchers paid close attention to interleukin-6 (IL-6), a protein involved in inflammation. IL-6 levels are often elevated in children with ADHD and is known to influence melatonin secretion. Pathway analysis confirmed that key IL-6 signaling were strongly linked to both melatonin production and ADHD symptoms.
“Our findings indicate that disruptions in melatonin secretion may contribute to the difficulties children with ADHD face in maintaining regular sleep patterns,” said Nagahide Takahashi, visiting associate professor, Hamamatsu University School of Medicine. “This could potentially worsen their ADHD symptoms, creating a vicious cycle that can be challenging to break.” Takahashi is also the lead author of the study and a clinical expert of ADHD.
While melatonin supplementation could be a promising intervention, more studies are needed to understand its long-term effects. In the meantime, parents and guardians can focus on supporting melatonin’s natural rhythms by encouraging routines that include adequate daylight exposure, minimized evening screen time and dimmed lights before bedtime.
For adults who are still managing ADHD, small, mindful lifestyle adjustments like these may also help in improving focus, sleep quality and overall well-being.
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Source: Hamamatsu University School of Medicine ; Image: Yipei Lieu/ Asian Scientist Magazine
The article can be found at Association between genetic risk of melatonin secretion and attention deficit hyperactivity disorder.
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