Single-Session HRV Biofeedback Alters Neural Activity but Not Subjective Anxiety

In healthy adults, single-session HRV biofeedback during paced breathing increased EEG delta and theta power and broadened alpha/beta changes, without improving STAI-S state anxiety versus paced breathing alone.

• Why it matters: Anxiety and stress are common, but effective low-cost options are limited; this study tests whether HRV biofeedback adds benefit beyond paced breathing and whether neural and self-reports align.
• What they did: After a speeded Stroop stress induction, participants completed a ten-minute paced breathing exercise under either HRV biofeedback (real-time variability displayed) or a no-feedback control with the same breathing cue; state anxiety used STAI-S and EEG spectral power across delta, theta, alpha, and beta.
• The result: Stroop elevated state anxiety and paced breathing reduced STAI-S equivalently in both groups, while HRV biofeedback produced more extensive, sustained spectral modulation in EEG bands, indicating neural engagement without additional subjective relief.

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