Could Airborne Pollen Alter Sleep in Non-Allergic Individuals? A Critical Hypothesis on Respiratory Oxidative Signalling, TRPA1 and Arousal

This critical narrative review examines whether airborne pollen could plausibly alter susceptibility to arousal during established sleep in non-allergic individuals through an allergy-independent respiratory sensory mechanism. The paper evaluates evidence linking pollen exposure to rapid airway oxidative signalling, endogenous TRPA1-active chemistry, respiratory trigeminal and vagal sensory pathways, and sleep arousal. Supporting, contradictory and null evidence are considered explicitly, and the major unresolved links in the proposed mechanism are identified. The evidence does not establish that ordinary environmental pollen exposure disrupts sleep in non-allergic humans. Rather, it supports a testable hypothesis and a staged experimental programme designed to determine whether environmentally realistic pollen exposure can generate sufficient TRPA1-active airway chemistry to alter arousal probability during sleep. This is a hypothesis paper and critical narrative review. No new experimental data are presented. The work is not peer reviewed.