The Effects of Chronic Partial Sleep Deprivation on Cognitive Functions of Medical Residents

Article excerpt

Objective: Because of on-call responsibilities, many medical residents are subjected to chronic partial sleep deprivation, a form of sleep restriction whereby individuals have chronic patterns of insufficient sleep. It is unclear whether deterioration in cognitive processing skills due to chronic partial sleep deprivation among medical residents would influence educational exposure or patient safety.

Method: Twenty-six medical residents were recruited to participate in the study. Participants wore an Actigraph over a period of 5 consecutive days and nights so their sleep pattern could be recorded. Thirteen participants worked on services that forced chronic partial sleep deprivation (<6 hours of sleep per 24h for 5 consecutive days and nights). The other thirteen residents worked on services that permitted regular and adequate sleep patterns. Following the 5-day sleep monitoring period, the participants completed the three following cognitive tasks: (a) the Wisconsin Card Sorting Test (WCST) to assess abstract reasoning and prefrontal cortex performance; (b) the Time Perception Task (TPT) to assess time estimation and time reproduction skills; and (c) the Iowa Gambling Task (IGT) to assess decision-making ability.

Results: The results of independent samples t-tests found no significant differences between the group who was chronically sleep deprived and the group who rested adequately (all ps > .05).

Conclusion: These results may have emerged for several possible reasons: (a) chronic partial sleep deprivation may have a lesser impact on prefrontal cortex function than on other cognitive functions; (b) fairly modest chronic sleep restriction may be less harmful than acute and more significant sleep restriction; or (c) our research may have suffered from poor statistical power. Future research is recommended.

Keywords: Cognition, Executive function, Internship and residency, Sleep deprivation

Iran J Psychiatry 2010; 5:2:74-77

Medical residents are subjected to regular sleep restriction due to their on-call responsibilities. There has been significant concern about whether sleep restriction among medical residents could threaten their educational exposure or, more critically, patient safety (1). For example, some reports indicate that residents working frequent 12-hour overnight emergency room shifts show significant deterioration in visual memory and psychomotor vigilance from the beginning to the end of their duty (2-5). Kahol et al suggested that surgical proficiency, as assessed among junior- and senior-level residents, is significantly impeded when they are fatigued. This effect is manifested by an increased number of cognitive errors and decreased psychomotor efficiency and overall task performance. Cognitive skills are more affected than psychomotor skills; however, impeded cognitive performance may also lead to limited psychomotor proficiency. The decrement is significant in surgeons at all residency levels, and it must be considered when house officers are assigned post-call duties (2).

Barger et al also reported that extended-duration work shifts were associated with an increased risk of significant medical errors, adverse events, and attentional failures in interns across the United States. These results have important public policy implications for postgraduate medical education (5).

There are limited data examining the effects of chronic partial sleep deprivation (CPSD) on cognitive function of medical residents (1). This study examined whether medical residents' prefrontal cortex performance was affected by CPSD.

Materials and Methods

A convenience sample of 26 medical residents of Kermanshah University of Medical Sciences (KUMS) was recruited to participate in the study. Exclusion criteria included acute or chronic medical or psychiatric illness, use of any medications, and pregnancy. All participants provided informed consent to participate in the research, and the study protocol was approved by the Ethics Committee of Kermanshah University of Medical School (KUMS). …