Zenodo · Jun 4, 2026
Sundowning Syndrome Reinterpreted Through Classical Oriental Medicine: An OMN™ Yangming Heat Model of Nocturnal Behavioral Escalation in Dementia
By Ishihara S
Abstract Sundowning Syndrome is a well-recognized neuropsychiatric phenomenon in dementia patients, characterized by agitation, confusion, wandering, and hallucinations that emerge or worsen from late afternoon into the night. Despite its clinical prevalence, the underlying mechanisms remain poorly understood, and no established pharmacological treatment exists. This paper reinterprets Sundowning Syndrome through the theoretical framework of Oriental Medicine Neurodynamics (OMN™) and proposes a novel explanatory model: periodic ascending disruption of Shen (神識; conscious awareness) driven by chronic Yangming excess heat (潮熱サイクル; tidal heat cycle). OMN™ is a theoretical system developed by the author over more than 30 years of clinical practice, reinterpreting classical Oriental medical texts — including the Huangdi Neijing (Suwen, Lingshu), Nanjing, and Shanghan Lun — through the lens of autonomic neuroscience and neurophysiology. Ishihara S. | OMN™ | Sundowning Syndrome & Yangming Heat | SSRN Preprint 2026 | 1Three central arguments are presented. First, dementia can be differentiated into three distinct pathological patterns: the Deficiency type (健忘型; memory predominant, characterized by Kidney vacuity), the Liver-Gallbladder type (肝胆型; characterized by emotional agitation and Wood qi excess), and the Yangming type (陽明型; characterized by delusion, instinctual behavioral outbursts, and complete loss of verbal communication). Second, the temporal pattern of Sundowning — symptom escalation specifically from late afternoon into the night — corresponds precisely to the tidal heat (潮熱; cháo rè) cycle described in Shanghan Lun Article 212, composed more than 2,000 years ago. Third, the classical concept of zhàngyǔ (讝語; delirious speech with complete loss of communicative capacity) provides a precise framework for understanding nocturnal behavioral outbursts in dementia patients, including what this paper terms "behavioral zhàngyǔ" — instinctual physical activity as an expression of Shen ascent when verbal output is no longer possible. A clinical observation is reported in which nocturnal agitation resolved within approximately one month following dietary restriction as the primary yangsheng (養生; lifestyle cultivation) intervention, offering preliminary support for the theoretical model. This paper introduces a framework derived from more than two millennia of clinical tradition to address questions that remain unresolved in contemporary medicine. It does not propose a clinical guideline, but rather explores the theoretical possibility of interpreting Sundowning through classical Oriental medical concepts.