Attention Deficit Hyperactivity Disorder (ADHD) is one of the neurodevelopmental disorders that is
characterized by two types of cognitive symptoms, namely: inattention and hyperactivity-impulsivity, in the Diagnostic and
Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Also, there are non-cognitive symptoms of ADHD that are
not listed in ADHD such as excessive daytime sleepiness and fatigue. Most of the existing causal models of ADHD are
cognitive, brain-centric, non-embodied models. Among these, the triple-pathway model introduced by Sonuga-Barke et al.
(2010) is currently one of the most widely accepted hypothetical models of ADHD. However, this model has a weak
explanatory power because it can at most explain the above-mentioned two cognitive symptom types and cannot explain
non-cognitive symptoms of excessive daytime sleepiness and fatigue. Another existing model, the State Regulation Deficit
(SRD) Model, is a non-cognitive model of ADHD that explains ADHD symptoms including a non-cognitive symptom of
excessive daytime sleepiness in terms of arousal dysregulation. However, the SRD model does not offer the explanation of
why arousal dysregulation occurs in ADHD patients and why they tend to feel fatigued in everyday life. To overcome these
weak points of the SRD model, in this paper, I will offer a new, non-cognitive, non-brain-centric, embodied model, which I
call the “restless model”, of ADHD. This model explains that ADHD patients tend to be “restless”, i.e., bad at taking rest and
therefore they often feel sleepy and fatigued. Behind this tendency of restlessness in ADHD patients, the restless model posits
dysfunction of the autonomic nervous system, and in that sense, is non-brain-centric (embodied). If this embodied model is
valid, it will not only have implications for understanding of ADHD but also for treatments of the disorder.
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