The interaction between sleep quality and academic performance

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Abstract

Sleep quality has significant effects on cognitive performance and is influenced by multiple factors such as stress. Contrary to the ideal, medical students and residents suffer from sleep deprivation and stress at times when they should achieve the greatest amount of learning. In order to examine the relationship between sleep quality and academic performance, 144 medical students undertaking the pre-clinical board exam answered a survey regarding their subjective sleep quality (Pittsburgh sleep quality index, PSQI), grades and subjective stress for three different time points: semester, pre- and post-exam. Academic performance correlated with stress and sleep quality pre-exam (r = 0.276, p < 0.001 and r = 0.158, p < 0.03, note that low performance meant low sleep quality and high stress), however not with the stress or sleep quality during the semester and post-exam. 59% of all participants exhibited clinically relevant sleep disturbances (PSQI > 5) during exam preparation compared to 29% during the semester and 8% post-exam. This study shows that in medical students it is not the generally poor sleepers, who perform worse in the medical board exams. Instead students who will perform worse on their exams seem to be more stressed and suffer from poor sleep quality. However, poor sleep quality may negatively impact test performance as well, creating a vicious circle. Furthermore, the rate of sleep disturbances in medical students should be cause for intervention.

Introduction

Many findings in recent years point toward the importance of sleep for memory consolidation: Sleep seems to stabilize as well as enhance a wide variety of memory contents (Diekelmann and Born, 2010). Not only the consolidation of memories, also the encoding itself is negatively influenced by sleep deprivation (Van Der Werf et al., 2009; Yoo et al., 2007; Van Der Werf et al., 2011). Furthermore, sleep inspires insight into hidden rules and facilitates generalization of knowledge (Ellenbogen et al., 2007; Gómez et al., 2006; Wagner et al., 2004). All these cognitive competences are of great importance during higher education, often considered the most demanding and challenging learning period in many people's life. Especially medical students are expected to retain a large amount of complex factual knowledge in a comparably short time period.

Many studies strongly suggest that timing of sleep as well as its quality and quantity are linked with students' learning abilities and academic achievement and that students are often chronically sleep deprived (Curcio et al., 2006; Wolfson and Carskadon, 2003). Studies have indicated that over 60% of college students were poor-quality sleepers, resulting in daytime sleepiness and an increase of physical and psychological health problems (Lund et al., 2010; Sing and Wong, 2010). Another study investigating medical-students could not only show significant sleep disturbances, these problems were also related to depressive symptoms (Eller et al., 2006). Beebe et al. (2010) restricted sleep in a simulated classroom, which led to lower quiz scores, more inattentive behaviors and lower arousal. Due to an impressive workload sleep disturbances seem especially prevalent in medical students and residents (Nojomi et al., 2009), an alarming fact considering the clinical responsibilities of these populations. People working in medical fields also often suffer from large amounts of stress; and stress and sleep have long time been known to co-enact with each other (Friedman et al., 1995; Hall et al., 2000; Kachikis and Breitkopf, 2012; Morin et al., 2003; Van Reeth et al., 2000; Kashani et al., 2011). Acute and chronic stressors have pronounced effects on sleep architecture and circadian rhythms and sleep deprivation is a stressor (Van Reeth et al., 2000). Both sleep and stress are closely linked to the hypothalamo-pituitary-adrenal (HPA) axis, which explains the close interrelationship between these two factors (Steiger, 2003; Van Reeth et al., 2000).

In a recent study (Genzel et al., sub) investigating circadian rhythms and academic performance in a side-analysis we observed a significant correlation between current sleep quality and performance in the pre-clinical board exam in medical school. However, the sleep quality was assessed over one year after the board exams, and a causal relationship could not be determined. We therefore investigated in a new sample the sleep quality and stress levels in students before, during and after exam preparation for the pre-clinical board-exams with the goal to further clarify the relationship between sleep, stress and academic performance.

Section snippets

Procedures

The pre-clinical board-exam is the first comprehensive examination within medical school in Germany and takes place after four semesters. During the preceding 2 months no classes are scheduled to enable a free learning period. The successful completion of the exams allows medical students to enter clinical training.

For this study, 943 medical students of the University of Munich, who were eligible to take the pre-clinical board-exams, were asked to participate in a web-based survey. Of the 943

Results

The average grade of the 144 students in this study did not significantly differ from the grades achieved by all 632 students taking the exam at the university (mean ± SD 2.57 ± .88 and 2.61 ± .78 respectively, T774 = 0.595, P > 0.5).

Academic performance was associated with the level of stress and sleep quality pre-exam (stress: r = 0.276, P < 0.001; PSQI: r = 0.158; P < 0.03; note that low performance meant low sleep quality and high stress, see Fig. 1), however not during the semester or

Discussion

This study showed that academic performance is linked to sleep quality and stress prior to the exam. Both stress and sleep quality correlated with exam grades, note that low performance meant low sleep quality and high stress; yet, this relationship was not found for the other time points. It seems however that those students who generally sleep poorly do not receive bad grades. Perceived stress has been identified as one major factor contributing to these low scores in sleep quality, resulting

Author disclosure

All authors report no conflict of interest.

Contributors

K.A. and L.G. designed, performed and analyzed the study. K.A. wrote the first draft of the article. S.N., A.S and M.D. helped design and analyze the study. All authors contributed to writing and discussing the article.

Role of the funding source

The study was funded by the Max Planck Institute of Psychiatry.

Acknowledgments

We would like to thank Karin Samson for the help recruiting the subjects. Further we would like to thank the participants for answering the questionnaire.

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      Numerous studies observed that medical students are particularly exposed to the risk of developing sleep disorders [1,3] compared to the general population or students in other fields [3]. Depending on the country, the prevalence of poor sleep quality among medical students, as assessed by the Pittsburgh Sleep Quality Index (PSQI), ranges from 29% in Germany [4] to 40% in Lithuania [5]. Some causative factors have been suggested such as the particular important academic load, but also students’ attitudes and knowledge about sleep [6].

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