Acute Sleep Deprivation Is Associated with Altered F-Wave Temporal Dynamics and Nasalis Repetitive Nerve Stimulation Responses: A Paired Electrophysiological Study.

BACKGROUND: Acute sleep deprivation affects cortical excitability and cognition, but its association with spinal motor output and repetitive nerve stimulation (RNS) responses is insufficiently characterized. We evaluated F-wave parameters and low-frequency RNS before and after an overnight on-call period. METHODS: In this prospective paired within-participant study, 30 healthy resident physicians underwent standardized electrophysiological assessments before and after an overnight on-call period involving approximately 24 h of self-reported continuous wakefulness. Fatigue was assessed using the Fatigue Impact Scale (FIS). Posterior tibial nerve F-wave stimuli and 3 Hz nasalis RNS stimuli were delivered at each session. Paired parametric or non-parametric tests were selected according to the distribution of within-participant differences, with Benjamini-Hochberg false discovery rate (FDR) correction across electrophysiological comparisons. RESULTS: FIS scores increased after the on-call period. F-wave maximum latency and chronodispersion increased, whereas persistence decreased; minimum latency was unchanged. The signed first-to-fourth compound muscle action potential (CMAP) amplitude change shifted in the decremental direction, while baseline CMAP amplitude remained stable. RNS values at both sessions were within physiological limits. CONCLUSIONS: Acute overnight sleep deprivation was associated with altered F-wave temporal organization and a small directional shift in nasalis RNS responses. The RNS finding was statistically significant, but does not constitute evidence of pathological neuromuscular transmission failure. Larger studies with objective sleep monitoring, additional muscles, more F-wave stimuli, and recovery measurements are required.