PADA Hypothesis: The Axis Model of Photoperiod‑Driven Receptor Desensitization and Aging (PADA‑V2‑ENGLISH)

This archival preprint presents the complete PADA‑V2 hypothesis system (Photoperiod‑Adenosine‑Desensitization‑Aging), a falsifiable mechanistic framework investigating sleep pressure and ageing‑related stress driven by adenosine‑receptor signalling. Departing from the conventional single‑variable adenosine‑concentration‑centric paradigm, PADA introduces a second independent regulatory variable: GRK‑mediated homologous desensitization (D) of A₁/A₂A adenosine receptors. Downstream G‑protein‑mediated physiological outputs are jointly determined by extracellular adenosine ligand concentration and receptor desensitization status, rather than adenosine concentration alone. The manuscript strictly enforces a six‑level academic hierarchy to separate Level‑0 peer‑reviewed empirical facts, first‑order inferences, second‑order deductions, third‑order constructs, fourth‑order ultimate hypotheses and fifth‑order limit thought‑experiments. All non‑factual statements are equipped with explicit positive predictions and negative falsification criteria. Material from a retrospective N‑of‑1 long‑term self‑observation is included exclusively as heuristic phenomenological reference; it does not constitute proof of molecular‑level causality, and self‑replication of extreme short‑sleep patterns is strongly discouraged. The Room‑Six photoperiod‑intervention construct is a purely theoretical thought‑experiment without human trial data and must not be adopted as real‑world wellness guidance. This work documents the retired PMXAA intermediate paradigm, proposes a four‑part molecular‑derived insomnia/short‑sleep typology (distinct from the ICSD‑3 clinical diagnostic system), and defines a full tiered V3 experimental roadmap spanning in‑vitro cellular assays, animal‑model validation and non‑interventional human observational cohorts. Chapter 10 advances natural‑philosophy‑oriented reasoning concerning biological‑time remodelling and ageing boundaries, with clear demarcation between testable hypotheses and philosophical speculation. Important disclaimer: The PADA system represents a collection of scientific hypotheses, not experimentally verified conclusions. It is intended for hypothesis archiving and experimental‑design reference only. It cannot replace clinical sleep‑medicine standards and must not be used for clinical diagnosis, therapy or self‑directed human physiological interventions. Supplementary raw‑draft appendices are hosted separately on Zenodo under associated DOIs.