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Hosseini S M, Nazarinejad M, Habibikoolaee M. Impact of a Single Internship Night Shift on Cognitive Processing Speed and Patient Safety Implications Among Medical Interns: A Pre-Post Study Using the Digit Symbol Substitution Test. mededj 2026; 15
URL: http://mededj.ir/article-1-602-en.html
URL: http://mededj.ir/article-1-602-en.html
Department of Health Information Technology, School of Allied Medical Sciences, Golestan University of Medical Sciences, Gorgan, Iran
Abstract: (7 Views)
Background and Objective: Long night shifts of medical interns expose them to acute sleep deprivation, which may impair cognitive functions and compromise patient safety. This study aimed to objectively evaluate the impact of a single night shift on the cognitive processing speed of medical interns using the Digit Symbol Substitution Test (DSST).
Methods: In this pre-post prospective study, 60 medical interns from Golestan University of Medical Sciences were enrolled in 2024. Cognitive performance was assessed using the standardized DSST at two time points: before the shift (baseline) and immediately after the night shift. Data were analyzed using paired t-test, independent t-test, and ANOVA.
Findings: The mean DSST score decreased significantly from 60.87 ± 9.96 before the shift to 53.58 ± 10.09 after the shift, indicating an 11.96% decline in processing speed and attention (P < 0.001). Subgroup analyses revealed that married interns demonstrated significantly higher baseline DSST scores compared to single interns (P = 0.048). Moreover, tuition-free students demonstrated significantly better cognitive performance than tuition-paying (international campus) students both before (P = 0.014) and after the shift (P = 0.039). Gender, age, clinical ward, shift duration, and patient load showed no significant impact.
Conclusions: A single night shift leads to a significant meaningful decline in interns' cognitive processing speed, potentially increasing the risk of medical errors during late shift hours. Revising shift structures and incorporating supportive protocols, such as strategic napping, into the medical curriculum appear essential for enhancing patient safety.
Methods: In this pre-post prospective study, 60 medical interns from Golestan University of Medical Sciences were enrolled in 2024. Cognitive performance was assessed using the standardized DSST at two time points: before the shift (baseline) and immediately after the night shift. Data were analyzed using paired t-test, independent t-test, and ANOVA.
Findings: The mean DSST score decreased significantly from 60.87 ± 9.96 before the shift to 53.58 ± 10.09 after the shift, indicating an 11.96% decline in processing speed and attention (P < 0.001). Subgroup analyses revealed that married interns demonstrated significantly higher baseline DSST scores compared to single interns (P = 0.048). Moreover, tuition-free students demonstrated significantly better cognitive performance than tuition-paying (international campus) students both before (P = 0.014) and after the shift (P = 0.039). Gender, age, clinical ward, shift duration, and patient load showed no significant impact.
Conclusions: A single night shift leads to a significant meaningful decline in interns' cognitive processing speed, potentially increasing the risk of medical errors during late shift hours. Revising shift structures and incorporating supportive protocols, such as strategic napping, into the medical curriculum appear essential for enhancing patient safety.
Keywords: Cognitive Function, Neuropsychological Tests, Patient Safety, Medical Student, Shift Work Schedule
Type of Study: Research |
Subject:
General
Received: 2026/06/28 | Accepted: 2026/09/26 | Published: 2026/04/4
Received: 2026/06/28 | Accepted: 2026/09/26 | Published: 2026/04/4
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This work is licensed under a Creative Commons Attribution-NonCommercial (CC BY-NC)