Sleep quality, sleep habits, and chronotypes of medical interns at the beginning of their training
Introduction: Despite the implementation of resident work hour regulations, studies
have not consistently shown beneficial changes in residents’ sleep quality or duration. We
hypothesized that inter-individual sleep-related differences may exist prior to training and the
pre-existing sleep health and habits may impact training.
Objective: To determine interns’ baseline sleep quality, sleep hygiene, chronotypes, and
their correlates at the beginning of their residency training program.
Methods: A cross-sectional study using an anonymous “Resident Sleep Survey” included
baseline demographic information and questionnaires, including the Epworth Sleepiness
Scale (ESS), the Pittsburgh’s Sleep Quality Index (PSQI), the Morningness-Eveningness
Questionnaire (MEQ), and the Sleep Hygiene Index (SHI).
Results: One hundred and twenty-nine subjects participated the study; 45.7 % (n=59)
were male and 18.6 % (n=24) were married. Twenty percent of interns had an ESS >10. The
PSQI revealed that 28% of interns had poor sleep hygiene. The mean sleep efficiency was
91.2 ±7.4% estimated from the PSQI. Non-married interns had a lower prevalence of morning
chronotypes (22.3% vs. 45.8%, p=0.02). Morning chronotype interns had a lower ESS score
(6.1 ±3.1 vs. 7.6 ±3.6, p=0.03) and a lower SHI (29 ±7.0 vs. 34.3 ±7.1, p=0.003).
Conclusion: About a quarter of interns had poor sleep quality and excessive daytime
sleepiness prior to their training. Non-morning chronotype interns appeared to have more
daytime sleepiness and poorer sleep quality. Since pre-existing sleep problems may adversely
affect learning, we suggest that strategies to improve sleep hygiene and quality in this specific
population should be emphasized early in their training.
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