Comment on Kaplan et al.: Interpreting Cognitive and Handover Associations During Night Shifts

We read with interest the study by Kaplan et al. ( 2026 ) on sleepiness, self-reported cognitive control and flexibility, and self-reported handover effectiveness among 270 nurses working 16-hour night shifts.The authors acknowledge the cross-sectional design, inability to establish causality, exploratory and unadjusted structural equation model, and absence of objective performance measures.Our principal contribution concerns what the cognitive measure represents: relatively stable perceived abilities or acute within-shift impairment.This distinction, alongside the interpretation of time-specific correlations and the shared nature of handover, may refine the meaning of the reported associations.