Introduction: Reduced or interrupted sleep directly results in deleterious effects on the health of those affected. Plastic and reconstructive surgery registrars are often subject to high on-call workloads, with seemingly constant disruptions and reductions in sleep. This study aims to quantify the effect of this on the health of the subject by examining heart rate variability (HRV), an evidence-based marker of cardiovascular health, and it’s change during an extended period of 1-in-2 on call at an urban trauma centre. Secondary markers of evaluation include calculated sleep debt, and recovery. Methods: data obtained from a registrar from an urban quaternary trauma centre’s WHOOP band was retrospectively reviewed. Results: HRV at the commencement of the examined period was 68ms, considered healthy for age. At the end of the examined period, HRV was 45ms, a 33% reduction. Sleep debt was 25 minutes at the commencement of the period and had increased to 1:52hrs at the completion. Recovery decreased from 72% to 53%. Conclusions: high on-cal workloads have a demonstrably deleterious effect on the health of the registrar. Solutions to ensure adequate periods of rest should be explored to limit the effect of these times.