Post-occlusive reactive hyperemia following acute mental stress in healthy young subjects: a randomized crossover photoplethysmography study.

Acute mental stress may modify peripheral vascular tone, potentially complicating the interpretation of post-occlusive reactive hyperemia (PORH). This randomized crossover study examined whether a Stroop-based mental stress protocol alters cutaneous PORH and whether bilateral photoplethysmography (PPG) can distinguish changes in the peripheral vascular background from the local post-occlusive response. Twenty-six healthy young participants completed Rest and Stress protocols in randomized order, each comprising a 10-min pre-occlusion period, 5 min of suprasystolic arterial occlusion, and 10 min of recovery. Bilateral PPG waveform amplitude, skin temperature, and electrodermal activity (EDA) were recorded. Absolute PPG amplitude was lower during the Stress protocol both before occlusion and during subsequent phases, with similar differences in the contralateral non-occluded limb. In contrast, baseline-referenced measures of PORH magnitude did not differ between protocols, and contralateral-adjusted analyses likewise provided no robust evidence of altered local hyperemic responsiveness. The Stroop protocol elicited an initial EDA response and a bilateral decrease in skin temperature, confirming peripheral physiological effects with different temporal profiles. These findings show that differences in absolute post-occlusive PPG amplitude do not necessarily indicate altered PORH. Under the present experimental conditions, the principal differences between Rest and Stress concerned the bilateral peripheral vascular background rather than the magnitude of the locally evoked post-occlusive response.