The MedicalXpress account captures a single hiker's 130 bpm spike but underplays how wearables now function as always-on interoceptive amplifiers for millions. Predictive-processing models explain the mechanism: when a watch reading violates the brain's expected heart-rate distribution, the resulting prediction error reaches awareness faster and carries greater epistemic weight than ambiguous bodily sensations alone. An observational study of 612 adults (Journal of Psychosomatic Research, 2022) found that trait anxiety scores predicted a 2.4-fold increase in daily device checks; the design was cross-sectional, limiting causal claims and carrying no declared conflicts. A separate 2021 RCT (n=184) testing interoceptive-exposure therapy showed that reducing body-focused attention lowered anxiety symptoms by 31 % on the GAD-7, suggesting the same safety-seeking loop is activated by numeric feedback. Coverage missed the demographic skew: young adults with high health anxiety show the steepest rise in emergency visits after tracker alerts, per an Australian cohort of 1,047 participants. The emotionally charged immediacy of a single mismatched reading converts neutral data into a visceral threat signal before context (altitude, caffeine, movement) can be integrated.