Interoceptive-autonomic pathways in mood state transitions in bipolar disorder: a hypothesis-generating brief review

Bipolar disorder is typically described in terms of clinical states such as depression, mania, or hypomania, but bodily signal processing, autonomic regulation, and emotion regulation across these states have not yet been integrated into a single testable model. This review distinguishes cross-sectional correlates of mood states from longitudinal predictors of subsequent mood changes. It proposes a state-dependent framework linking sleep–circadian disruption, autonomic flexibility, interoceptive processing, and emotion regulation; the temporal sequence and causal contributions of these components remain unestablished. Cross-sectional findings describe concurrent associations, recovery studies characterize changes accompanying symptom resolution, and prospective studies inform temporal ordering and prediction; none alone establishes a mechanism driving mood-state transitions. This article discusses direct evidence from bipolar disorder, transdiagnostic evidence, and theoretical inference in a hierarchical manner, without equating HRV with interoception or treating altered interoception as a single pathophysiological mechanism of bipolar disorder. Finally, it proposes a research protocol comprising state-stratified heartbeat discrimination/signal detection tasks, HRV reactivity and recovery, sleep and activity rhythms, ecological momentary assessment (EMA), and longitudinal assessment of state transitions.