Sleep Quality and Duration Can Influence Junior Physicians' Performance in High-Level Assessments for Residency Programs

Keywords

sleep quality - sleep duration - physicians - performance - clinical assessment - undergraduate medical education

Introduction

The importance of sleep and the health risks related to the sleep deprivation are described in all species. In particular, cognitive function, psychomotor skills, and increased drowsiness are among the impaired functions associated with sleep deprivation in humans.[1] Furthermore, the sleep deprivation has been associated with higher risk of cardiovascular diseases [2] and changes in glucose metabolism and hormone regulations.[3]

In fact, research evidence has largely demonstrated that sleep is crucial for human cognitive functions, memory consolidation (long-term potentiation), and learning processes.[4]

Given the importance of high-level evaluations in determining junior physicians' access to residency programs, it is worthwhile to investigate the relationship between students' sleep quality and their academic performance.[5] Sleep deprivation or poor sleep quality can negatively impact attention, decision-making ability, executive functions, and overall cognitive performance.[6] [7] Thus, poor sleepers tend to perform worse on tasks that require complex cognitive processing and sustained attention, which are key components in academic performance evaluations.[8] [9]

Numerous studies have investigated the relationship between sleep quality and the academic performance of medical students and junior physicians, reporting a significant correlation between inadequate sleep quality and lower academic achievement.[10] [11] Also, recent research evidence has explored the complex relationships between sleep, mood, and academic outcomes,[12] demonstrating that poorer sleep quality and increased daytime sleepiness were both associated with a reduced academic performance [13]

In Paraguay, medical students from both public and private universities generally graduate in December of each year. Three months later, in March, they face a single standardized assessment to gain access to the residency programs for primary and derived specialties, provided by the National Commission for Medical Residencies (Comisión Nacional de Residencias Médicas – CONAREM, in Spanish). The CONAREM's written evaluation includes a set of questions about Internal Medicine, Surgery, Pediatrics, Gynecology and Obstetrics, and Public Health, which require exceptional cognitive capabilities and proficient decision-making skills.

Given the explored connection between sleep quality and cognitive performance, we aimed to test if junior physicians with sleep issues might struggle to attain their maximum potential results during this appraisal. The present study, which is the first in South America and particularly in Paraguay, aimed to examine the connection between sleep quality and the academic performance of physicians involved a rigorous evaluation for admission into medical residency programs. Inspired by the study design of a study published by Falloon et al.,[5] we assessed the quality and duration of sleep of physicians during the month and the night prior to the written exam for access to the primary specialty medical residency programs and then compared these data with their academic performance reported in the evaluation. Furthermore, we tested the potential associations between various sociodemographic factors, such as sex, lifestyle-related elements, including the consumption of caffeinated beverages and yerba mate (which is rich in methylxanthines), and physicians' health status, the presence of physical or mental illnesses, and their sleep quality.

Materials and Methods

Design and Sampling

This was an observational, descriptive, cross-sectional study[14] based on a survey conducted between March 6 and 7, 2024. The sampling was nonprobabilistic and consisted of consecutive cases.

Participants

The study included physicians of both sexes who performed the written evaluation for access to the primary specialty medical residency programs of CONAREM in March 2024 and agreed to participate by signing an informed consent form. Participants were informed of the research objectives and received the data collection instrument via messaging services. Only those who voluntarily agreed and completed the entire survey were included in the study, while those who did not complete the full evaluation were excluded. The internet-based approach was advantageous, as online survey responses can yield results similar to those obtained from “in-person” samples.[15] All participants were fully informed about the privacy measures and data handling procedures.

Measures

Sociodemographic Data

Participants were asked to report their sex (male or female), age, place of residence (Asunción City, Greater Asunción, rest of the country), marital status (single, married, in a partnership, divorced/separated, widowed), whether they had children (how many), and their living arrangement (alone, with a partner, family, or friends).

Academic Data

Participants' final scores in the CONAREM's written evaluation were obtained from the official records of the CONAREM (scale of 1–100).

Lifestyle-related Data

Participants were asked whether they had engaged in physical activity in the last month (number of days with at least 30 minutes of moderate-intensity physical activity in a typical week: none, 1–2, 3–4, 5–6, every day), about their consumption of mate and tereré (how many times per day), consumption of caffeinated beverages in the last month (none, 1–2, 3–4, 5, or more), how many days a week they had breakfast in the previous month, and whether they consumed alcohol, tobacco, or electronic cigarettes.

Health Status

Participants reported whether they suffered from a physical or mental illness (if yes, which one).

Quality and Quantity of Sleep

Participants were asked to report their quality and quantity of sleep in the previous month using the Pittsburgh Sleep Quality Index (described below). Additionally, participants reported the quality and quantity of sleep as well as use of hypnotics the night before their written evaluation for the access to the CONAREM's primary specialty medical residency programs.

The Pittsburgh Sleep Quality Index (PSQI)

The Pittsburgh Sleep Quality Index (PSQI) [16] was employed to rate the quality of sleep, specifically the Spanish version developed by Royuela and Macías.[17] The PSQI was administered electronically, with the approval of the University of Pittsburgh (United States). This assessment tool consists of 19 items categorized into 7 components: 1) Subjective sleep quality, 2) Sleep latency, 3) Sleep duration, 4) Habitual sleep efficiency, 5) Sleep disturbances, 6) Use of sleep medication, and 7) Daytime dysfunction. The PSQI total score ranges from 0 to 21, with scores of 0 to 5 indicating “good sleepers” and 6 to 21 indicating “poor sleepers” (diagnostic sensitivity of 89.6% and specificity of 86.5%, kappa = 0.75, p < 0.001).[16] Recently, a useful categorization approach for the PSQI scores has been proposed, classifying scores between 6 and 10 as “moderately poor sleepers” and scores greater than 10 as “very poor sleepers”.[18] The Spanish version of the PSQI demonstrates an adequate internal consistency, with Cronbach's alpha ranging from 0.67 to 0.81 in 2 samples of university students and 0.75 in non-professional caregivers.[19]

Written Evaluation for the Access to the CONAREM Primary Specialty Medical Residency Programs

The admission process to the CONAREM's primary specialty medical residency programs is subject to regulations established and approved by the Paraguayan Ministry of Public Health and Social Welfare.[20] A crucial component of this process is the administration of a single standardized exam (CONAREM's written evaluation) covering the entire academic knowledge in the fields of Internal Medicine, Surgery, Pediatrics, Gynecology and Obstetrics, and Public Health. This exam consists of 140 questions, corresponding to 140 points. The total final score is obtained considering: 1. The median of the top 10 scores obtained in the exam corresponds to 100 final points; 2. A simple rule of 3 is used to determine the points corresponding to scores below the median; 3. Scores above the median receive 100 final points, and 4. The score of the written evaluation uses 3 decimals. Applicants seeking to enter these programs aim to achieve the highest possible score, ranging from 0 to 100. Upon completing all evaluation stages, the applicant must obtain at least 60% of the total score to be included in the list of preselected candidates.[20]

Sample Size

The sample size was calculated using the epidemiological package Epidat 4.2 (Pan American Health Organization, Health Board of Galicia, CES University of Colombia). Assuming a population of 1,510 registrants for the CONAREM written evaluation, an expected frequency of 56.9% of poor sleepers in the month prior to a high-level evaluation (5), a confidence level of 95%, and a precision of 5.5%, the minimum sample size was established for 259 participants.[21]

Data Management and Analysis

The Jamovi and RStudio programs were used for the data management and analysis. Descriptive statistics were employed to report the quality and duration of sleep in the month prior to the CONAREM written evaluation and on the night before this, as well as to report on the use of sleep medication. The quality of sleep in the night before the CONAREM's written evaluation was rated according to question 6 of the Spanish version of the PSQI[17] as “quite good,” “good,” “bad,” or “quite bad.” These categories were evaluated for their statistical association with the score obtained in the CONAREM's written evaluation (scale of 1–100) using analysis of variance (ANOVA). For sleep quality in the month prior to the CONAREM's written evaluation, the linear association between the total PSQI score[17] and the total score of the written evaluation was measured using the Pearson's correlation coefficient (Pearson's r).

Finally, based on the literature,[22] sleep duration was dichotomized into ≤ 6 hours of sleep (short sleep) and > 6 hours, to determine the proportion of students with shorter sleep duration. The linear association between the duration of sleep in the night before the CONAREM's written evaluation and the total score on this exam was measured using Pearson's r. The proportion of students with ≤ 6 hours of sleep and > 6 hours of sleep was evaluated for its statistical association with the score obtained in the CONAREM's written evaluation (scale of 1–100) using the student's t-test. The linear association between the average sleep duration in the month prior to the written evaluation and the total score on this evaluation was measured using Pearson's r.

Results

Among 407 physicians approached, 270 successfully completed the survey (response rate of 66.3%). Among the participants, 72.2% were female. Their ages ranged from 23 to 57 years, with a mean of 27.5 ± 4.51 years.

The average PSQI score was 10.4 ± 4.08. In the month before the CONAREM's written evaluation, 24 participants (8.9%) reported a good sleep quality (PSQI ≤ 5), 96 (35.6%) reported a moderately poor sleep quality (PSQI = 6–10), and 150 (55.5%) reported a very poor sleep quality (PSQI > 10). Women scored significantly higher on the PSQI (p = 0.013). The mean score on the CONAREM's written evaluation was 68.7 ± 13.5 (25.2% of the participants failed the test).

[Table 1] reports on participants' demographic characteristics and their relationship with the sleep quality in the previous month according to the reported PSQI scores.

Table 1 Demographics and their relationship with the PSQI scores in the past month (N = 270)

Characteristics	n	%	PSQI score		p-value
			Mean	SD
Gender					0.013
Male	75	27.8	9.41	4.22
Female	195	72.2	10.8	3.51
Place of residence					0.761
Asunción	71	26.3	10.7	4.1
Greater Asunción	87	32.2	10.2	4.42
Rest of the country	112	41.5	10.4	3.8
Marital status					NaN
Single	223	82.6	10.53	4.02
Married or partnered	45	16.7	10.09	4.23
Divorced or separated	2	0.7	4	0
Children					0.414
Yes	30	11.1	9.83	4.47
No	240	88.9	10.5	4.03
Number of children (n = 30)					NaN
1	20	7.4	10.65	4.2
2	6	2.2	11.5	2.88
3	3	1.1	3	0
4	1	0.4	4	−
Living arrangement					NaN
Alone	1	0.4	5	−
With partner or family	239	88.5	10.49	4.1
With friends	30	11.1	9.9	3.84

Abbreviations: NaN, not calculable due to insufficient observations; PSQI, Pittsburgh Sleep Quality Index; SD, standard deviation.

Note: In the SD column, “-” means that the SD does not exist or cannot be calculated.

Regarding the lifestyle characteristics of the participating physicians, a significant association was found between engaging in daily physical activity and better sleep quality scores (p = 0.013). It was also found that those who consumed caffeine 3 to 4 times (or more per day) during the month prior to the study reported worse sleep quality (p = 0.036) ([Table 2]).

Table 2 Lifestyle-related variables and their relationship with PSQI scores in the past month (N = 270)

Characteristics	n	%	PSQI score		p-value
			Mean	SD
Physical activity (days per week)					0.013
None	128	47.4	11.2	3.82
1–2 days	79	29.3	10.1	4.28
3–4 days	35	13	9.77	4.26
Every day	11	4.1	8.73	2.8
Yerba mate usage (times per day)					0.349
1–2	122	45.2	10.22	4.12
3–4	59	21.9	9.97	4.05
5 or more	26	9.6	10.46	4.53
No consumption	63	23.3	11.16	3.82
Caffeine consumption (times per day)					0.036
1–2	130	48.1	9.82	4.03
3–4	53	19.6	11.47	4.01
5 or more	33	12.2	11.39	3.72
None	54	20	10.19	4.24
Breakfast (days per week)					0.071
1–2	35	13	11.6	4.2
3–4	51	18.9	10.86	3.92
5–6	23	8.5	10.09	3.53
No days	18	6.7	11.94	4.01
Every day	143	53	9.81	4.1
Alcohol					0.083
Yes	122	45.2	9.93	3.75
No	148	54.8	10.8	4.3
Tobacco					0.677
Yes	8	3	11	4.96
No	262	97	10.4	4.06
Electronic cigarette					0.785
Yes	24	8.9	10.6	3.87
No	246	91.1	10.4	4.1

Abbreviations: PSQI, Pittsburgh Sleep Quality Index; SD, standard deviation.

Among the participants, 26 reported to be affected by a physical illness. Physical morbidity included: rheumatological (26.9%) = endocrine (26.9%) > pneumological (23.1%) > neurological (15.4%) > hematological, and dermatological (1%) illnesses. Regarding their mental health status, 18 participants reported to be affected by a mental disorder, as follows: anxiety disorders (61.1%) > depressive disorders (33.3%) > neurodevelopmental disorders (5.6%). The presence of physical illness (p = 0.012) and mental disorders (p = 0.003) was significantly associated with worse sleep quality in the previous month ([Table 3]).

Table 3 Participants' health status and its relationship with PSQI scores in the past month (N = 270)

Characteristics	n	%	PSQI score		p-value
			Mean	SD
Physical illness					0.012
Yes	26	9.6	12.3	3.89
No	244	90.4	10.2	4.05
Mental illness					0.003
Yes	18	6.7	13.1	3.86
No	252	93.3	10.2	4.03

Abbreviations: PSQI, Pittsburgh Sleep Quality Index; SD, standard deviation.

Quality of Sleep

The sleep quality in the month prior to the CONAREM's written evaluation (PSQI score) was not significantly correlated with the CONAREM's total score (r = − 0.0110, p = 0.918).

A significant relationship was found between the quality of sleep in the night prior to the CONAREM's written evaluation and the reported evaluation scores (f = 3.55, degrees of freedom [df] = 3, p = 0.019). Using the Tukey Post-Hoc test, it was determined that the significant different pair was comprised of “quite bad” and “good” sleep quality. Consequently, physicians with “quite bad” quality of sleep performed inferiorly on the exam in comparison to those who enjoyed “good” quality sleep (p = 0.009) ([Table 4]).

Table 4 Quality of sleep the night before the CONAREM written evaluation and its relationship with the scores obtained in the exam (N = 270)

Sleep quality	n	%	CONAREM scores		p-value
			Mean	SD
Quite good	16	5.9	68.7	20.7	0,019
Good	102	37.8	71.7	13.4
Bad	90	33.3	68	12
Quite bad	62	23	64.9	12.8

Abbreviations: CONAREM, Comisión Nacional de Residencias Médicas (Commission for Medical Residencies); SD, standard deviation.

Duration of Sleep

In the month prior to the CONAREM's written evaluation, 216 participants (80%) reported short sleep duration (≤ 6 hours of sleep), with an average of 5.49 hours (median: 5; standard deviation [SD]: ± 1.40; range: 10 [2–12]). Average sleep duration in the month prior to the CONAREM's written evaluation was not related to the score obtained (r = 0.253; p = 0.115).

On the night before the written evaluation, 215 participants (79.6%) slept ≤ 6 hours, with an average of 5.19 hours (median: 5; SD: ± 1.08; range: 12 [0–12]). A linear relationship was found between the duration of sleep on the night before the CONAREM's written evaluation and the total score obtained in the same evaluation (r = 0.200; p < 0.001), suggesting that the more hours they slept, the higher the score obtained.

Medication use

Regarding the use of sleeping medications, 84 participants (31.1%) used some sleep medication in the month prior to the CONAREM's written evaluation, whereas on the night before the evaluation, this figure was 16.3% (44 participants). The use of medications was not related to exam scores.

Among physicians who consumed medication in the month leading up to the CONAREM's written evaluation, 78.5% experienced poor sleep quality (PSQI ≥ 6) and 84.5% had short sleep duration (≤ 6 hours). Meanwhile, among those who took medication the night before the evaluation, 72.7% reported poor sleep quality (rated as “bad” or “quite bad” on question 6 of the PSQI) and 72.3% had short sleep duration (≤ 6 hours).

Discussion

The current study explored the relationship between sleep quality and academic performance in a sample of junior physicians facing a high-stake evaluation in South America. In our sample, over half of the participants reported very poor sleep quality (PSQI score > 10).

Sleep quality deficiencies are common among physicians. For instance, Machi et al. found that 31% of emergency physicians reported poor sleep quality.[23] During the coronavirus disease 2019 (COVID-19) pandemic, 68.3% of Iraqi physicians reported negative sleep impacts due to working with COVID-19 patients.[24] Similarly, the female physicians in our study scored higher on the PSQI, indicating significantly poorer sleep quality than male physicians. This finding aligns with those of Qi et al., who observed higher PSQI scores among female frontline medical workers,[25] and Surani et al., who reported similar results in Pakistan.[26] Factors contributing to poor sleep quality in women include hormones, depressive symptoms, anxiety, stress, and neurobiological mechanisms.[27] [28] [29] [30] [31] Addressing these issues is essential to improve sleep quality and wellbeing, particularly in vulnerable groups, such as physicians. Moreover, poor sleep quality has been linked to mental health conditions, such as posttraumatic stress disorder (PTSD), depression, and anxiety,[32] highlighting the need for targeted interventions.

We identified a correlation between daily physical activity and improved sleep quality, which is consistent with prior findings among medical students.[33] Similarly, Lecca et al. observed that physical activity mitigates sleep disturbances and daytime drowsiness among Italian physicians.[34] For physicians, incorporating regular physical activity could help counteract the negative effects of demanding work schedules.[33] [34] Conversely, consuming three or more caffeinated beverages daily was linked to poorer sleep quality in our sample. While caffeine enhances alertness and attention in sleep-deprived individuals,[23] its consumption later in the day disrupts sleep, as Drake et al. noted.[35] Although no direct association was found between yerba mate and sleep quality, its caffeine content warrants further investigation, particularly given its popularity in Paraguay.[36]

Physicians with rheumatological and endocrine disorders reported poorer sleep quality. Son et al. observed worse sleep in patients with rheumatological diseases, especially during acute phases.[37] Endocrine disorders, including obesity, type 2 diabetes, and thyroid imbalances, also disrupt sleep owing to their impact on circadian rhythms and hormonal balance.[38] [39] Furthermore, anxiety and depressive symptoms were strongly associated with poor sleep quality in our study. Previous research has highlighted the bidirectional relationship between sleep disturbances and mental health conditions, such as depression, anxiety, and PTSD.[32] [40] These findings emphasize the importance of addressing both physical and mental health factors to improve sleep quality in this population.

The consequences of poor sleep among physicians extend beyond their personal wellbeing. It increases the risk of medical errors [41] and negatively affects academic performance. Maheshwari and Shaukat found that inadequate sleep impaired medical students' academic performance, [42] and Elagra et al. observed similar effects among dental students during clinical practice.[43] El Hangouche et al. also found that PSQI scores ≥ 5 were associated with poor academic performance among medical students.[44] Our study found that over 90% of junior physicians were poor sleepers (PSQI ≥ 6), exceeding previous reports in other populations, including medical students in Pakistan,[26] [42] New Zealand,[5] and the general populations of Brazil [45] and Germany.[46]

Although no significant correlation was found between sleep quality in the month before the CONAREM's exam and the total scores, sleep quality on the night before the exam was significantly associated with performance. Physicians with “quite bad” sleep quality performed worse than those with “good” sleep quality. Pre-exam anxiety and stress are common contributors to poor sleep quality before high-stake assessments.[47] [48] Sleep duration also influenced performance: those who slept longer the night before the exam scored higher. Insufficient sleep duration impairs cognitive function, including reasoning and verbal skills.[49] Mirghani et al. and Bahamm et al. similarly reported that short nocturnal sleep adversely affects the academic performance of medical students.[50] [51] Moreover, inadequate sleep affects memory consolidation, as demonstrated by previous studies.[52]

Medication use was also a significant factor. In the month before the CONAREM's exam, 31.1% of participants reported using sleep medications, which decreased to 16.3% the night before. However, those who used these medications reported poor sleep quality and duration. Understanding the types and reasons for medication use among junior physicians is crucial, as misuse can lead to excessive sleepiness and failure to address underlying sleep issues.[53] Promoting healthy sleep habits and enhancing physicians' knowledge of sleep medicine are essential to mitigate these risks.[54] Education on healthy sleep hygiene and appropriate use of sleep aids is necessary to improve wellbeing and performance among junior physicians.

Our findings emphasize the need for strategies to support junior physicians during critical assessment periods. Improved sleep quality and longer sleep duration, particularly the night before examinations, are associated with better performance. Educating health care professionals about sleep hygiene is essential to promote their well-being and job performance. Furthermore, targeted interventions addressing physical and mental health conditions may improve sleep quality and overall outcomes in this population.

The present study has several strengths. To the best of our knowledge, this is the first study in South America to examine the impact of sleep quality on academic performance among junior physicians using an adequate sample size. These findings could inform long-term programs to improve physicians' sleep quality and overall wellbeing. However, this study also has limitations. Potential biases include the overrepresentation of women, which may have influenced the results. Additionally, the cross-sectional design limits causal inferences, and reliance on self-reported data introduces subjectivity.

In conclusion, over half of the physicians in our study reported poor sleep quality, with female physicians experiencing significantly worse outcomes. Physical activity and caffeine consumption were notable lifestyle factors affecting sleep, while mental and physical health also played significant roles. Better sleep quality and longer sleep duration the night before exams were correlated with higher scores, underscoring the importance of healthy sleep habits. The high use of sleep medications raises concerns, highlighting the need for continued monitoring and education. These findings emphasize the importance of addressing sleep quality to enhance junior physicians' performance and wellbeing.

• References

• 1 Agu AU, Esom EA, Chime SC, Anyaeji PS, Anyanwu GE, Obikili EN. Impact of Sleep Patterns on the Academic Performance of Medical Students of College of Medicine, University of Nigeria. Int J Med Health Dev 2021; 26 (01) 31-36
• 2 Hamer M, Batty GD, Kivimaki M. Sleep loss due to worry and future risk of cardiovascular disease and all-cause mortality: the Scottish Health Survey. Eur J Prev Cardiol 2012; 19 (06) 1437-1443
• 3 Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet 1999; 354 (9188) 1435-1439
• 4 Khan MA, Al-Jahdali H. The consequences of sleep deprivation on cognitive performance. Neurosciences (Riyadh) 2023; 28 (02) 91-99
• 5 Falloon K, Bhoopatkar H, Moir F, Nakatsuji M, Wearn A. Sleep well to perform well: the association between sleep quality and medical student performance in a high-stakes clinical assessment. Sleep Adv 2022; 3 (01) zpac019
• 6 Alhola P, Polo-Kantola P. Sleep deprivation: Impact on cognitive performance. Neuropsychiatr Dis Treat 2007; 3 (05) 553-567
• 7 Holding BC, Ingre M, Petrovic P, Sundelin T, Axelsson J. Quantifying Cognitive Impairment After Sleep Deprivation at Different Times of Day: A Proof of Concept Using Ultra-Short Smartphone-Based Tests. Front Behav Neurosci 2021; 15: 666146
• 8 Massar SAA, Lim J, Sasmita K, Chee MWL. Sleep deprivation increases the costs of attentional effort: Performance, preference and pupil size. Neuropsychologia 2019; 123: 169-177
• 9 Trockel MT, Menon NK, Rowe SG. et al. Assessment of Physician Sleep and Wellness, Burnout, and Clinically Significant Medical Errors. JAMA Netw Open 2020; 3 (12) e2028111
• 10 Abdulghani HM, Alrowais NA, Bin-Saad NS, Al-Subaie NM, Haji AM, Alhaqwi AI. Sleep disorder among medical students: relationship to their academic performance. Med Teach 2012; 34 (Suppl. 01) S37-S41
• 11 Gupta S, Prithviraj M, Gangwar A, Rath RS. Impact of Sleep Duration, Quality, and Chronotype on Learning and Academic Performance: A Cross-Sectional Study Among First Year Medical Students of a Tertiary Care Institute. Cureus 2023; 15 (12) e50413
• 12 Mehta KJ. Effect of sleep and mood on academic performance—at interface of physiology, psychology, and education. Humanit Soc Sci Commun 2022; 9: 16
• 13 Seoane HA, Moschetto L, Orliacq F. et al. Sleep disruption in medicine students and its relationship with impaired academic performance: A systematic review and meta-analysis. Sleep Med Rev 2020; 53: 101333
• 14 Torales J, Barrios I. Diseño de investigaciones. algoritmo de clasificación y características esenciales. Med Clín Soc 2023; 7 (03) 210-235
• 15 Gosling SD, Vazire S, Srivastava S, John OP. Should we trust web-based studies? A comparative analysis of six preconceptions about internet questionnaires. Am Psychol 2004; 59 (02) 93-104
• 16 Buysse DJ, Reynolds III CF, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res 1989; 28 (02) 193-213
• 17 Royuela A, Macías JA. Propiedades clinimétricas de la versión castellana del cuestionario de Pittsburgh. . [Clinimetric properties of the Spanish version of the Pittsburgh questionnaire] Vigilia-Sueno 1997; 9: 81-94
• 18 Soltani M, Haytabakhsh MR, Najman JM. et al. Sleepless nights: the effect of socioeconomic status, physical activity, and lifestyle factors on sleep quality in a large cohort of Australian women. Arch Womens Ment Health 2012; 15 (04) 237-247
• 19 Otero P, Simón MA, Bueno AM, Blanco V, Vázquez FL. Factorial Structure and Psychometric Properties of the Spanish Version of the Pittsburgh Sleep Quality Index in Non-Professional Caregivers. Healthcare (Basel) 2022; 11 (01) 67
• 20 Resolución SG. 690, de 30 de octubre, por la cual se aprueba el Reglamento General de Concurso para el Ingreso a las Residencias Médicas de la Comisión Nacional de Residencias - CONAREM,. para el ejercicio fiscal 2024 (30 de octubre de 2023
• 21 Muñoz Navarro SR. ¿Cuántos sujetos necesito para mi estudio?. Medwave 2014; 14 (06) e5995
• 22 Van Dongen HP, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. [published correction appears in Sleep. 2004;27(4):600] Sleep 2003; 26 (02) 117-126
• 23 Machi MS, Staum M, Callaway CW. et al. The relationship between shift work, sleep, and cognition in career emergency physicians. Acad Emerg Med 2012; 19 (01) 85-91
• 24 Abdellah MM, Khalil MF, Alhafiz A. Prevalence of Poor Sleep Quality Among Physicians During the COVID-19 Pandemic. Cureus 2021; 13 (01) e12948
• 25 Qi J, Xu J, Li BZ. et al. The evaluation of sleep disturbances for Chinese frontline medical workers under the outbreak of COVID-19. Sleep Med 2020; 72: 1-4
• 26 Surani AA, Surani A, Zahid S, Ali S, Farhan R, Surani S. To Assess Sleep Quality among Pakistani Junior Physicians (House Officers): A Cross-sectional Study. Ann Med Health Sci Res 2015; 5 (05) 329-333
• 27 Hrozanova M, Klöckner CA, Sandbakk Ø, Pallesen S, Moen F. Sex differences in sleep and influence of the menstrual cycle on women's sleep in junior endurance athletes. PLoS One 2021; 16 (06) e0253376
• 28 Fatima Y, Doi SA, Najman JM, Mamun AA. Exploring Gender Difference in Sleep Quality of Young Adults: Findings from a Large Population Study. Clin Med Res 2016; 14 (3-4): 138-144
• 29 Toyama N, Ekuni D, Taniguchi-Tabata A. et al. Associations between sleep bruxism, sleep quality, and exposure to secondhand smoke in Japanese young adults: a cross-sectional study. Sleep Med 2020; 68: 57-62
• 30 Segon T, Kerebih H, Gashawu F, Tesfaye B, Nakie G, Anbesaw T. Sleep quality and associated factors among nurses working at comprehensive specialized hospitals in Northwest, Ethiopia. Front Psychiatry 2022; 13: 931588
• 31 Dorsey A, de Lecea L, Jennings KJ. Neurobiological and Hormonal Mechanisms Regulating Women's Sleep. Front Neurosci 2021; 14: 625397
• 32 Angehrn A, Teale Sapach MJN, Ricciardelli R, MacPhee RS, Anderson GS, Carleton RN. Sleep Quality and Mental Disorder Symptoms among Canadian Public Safety Personnel. Int J Environ Res Public Health 2020; 17 (08) 2708
• 33 Vo L, Tran V, Nguyen T, Nguyen H, Tran V, Pham K. Sleep quality and associated factors among third-year medical students at can tho university of medicine and pharmacy. Tạp Chí Y Dược Học Cần Thơ 2023; (05) 29-35 https://doi.org/10.58490/ctump.2023i5.637
• 34 Lecca R, Bonanni E, Battaglia E. et al. Prevalence of sleep disruption and determinants of sleepiness in a cohort of Italian hospital physicians: The PRESOMO study. J Sleep Res 2022; 31 (01) e13377
• 35 Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med 2013; 9 (11) 1195-1200
• 36 Walton CM, Saito ER, Warren CE. et al. Yerba Maté (Ilex paraguariensis) Supplement Exerts Beneficial, Tissue-Specific Effects on Mitochondrial Efficiency and Redox Status in Healthy Adult Mice. Nutrients 2023; 15 (20) 4454
• 37 Son CN, Choi G, Lee SY. et al. Sleep quality in rheumatoid arthritis, and its association with disease activity in a Korean population. Korean J Intern Med (Korean Assoc Intern Med) 2015; 30 (03) 384-390
• 38 Uchima Koecklin KH, Shimosawa T, Li P. Editorial: Endocrine consequences of sleep disorders. Front Endocrinol (Lausanne) 2023; 14: 1238950
• 39 Morgan D, Tsai SC. Sleep and the endocrine system. Crit Care Clin 2015; 31 (03) 403-418
• 40 Meule A, Riemann D, Voderholzer U. Sleep quality in persons with mental disorders: Changes during inpatient treatment across 10 diagnostic groups. J Sleep Res 2023; 32 (02) e13624
• 41 Gustavsson K, Wierzbicka A, Matuszczyk M, Matuszczyk M, Wichniak A. Sleep among primary care physicians-Association with overtime, night duties and strategies to counteract poor sleep quality. J Sleep Res 2021; 30 (01) e13031
• 42 Maheshwari G, Shaukat F. Impact of Poor Sleep Quality on the Academic Performance of Medical Students. Cureus 2019; 11 (04) e4357
• 43 Elagra MI, Rayyan MR, Alnemer OA. et al. Sleep quality among dental students and its association with academic performance. J Int Soc Prev Community Dent 2016; 6 (04) 296-301
• 44 El Hangouche AJ, Jniene A, Aboudrar S. et al. Relationship between poor quality sleep, excessive daytime sleepiness and low academic performance in medical students. Adv Med Educ Pract 2018; 9: 631-638
• 45 Drager LF, Pachito DV, Morihisa R, Carvalho P, Lobao A, Poyares D. Sleep quality in the Brazilian general population: A cross-sectional study. Sleep Epidemiol 2022; 2: 100020
• 46 Hinz A, Glaesmer H, Brähler E. et al. Sleep quality in the general population: psychometric properties of the Pittsburgh Sleep Quality Index, derived from a German community sample of 9284 people. Sleep Med 2017; 30: 57-63
• 47 Rezaei M, Khormali M, Akbarpour S, Sadeghniiat-Hagighi K, Shamsipour M. Sleep quality and its association with psychological distress and sleep hygiene: a cross-sectional study among pre-clinical medical students. Sleep Sci 2018; 11 (04) 274-280
• 48 Eller T, Aluoja A, Vasar V, Veldi M. Symptoms of anxiety and depression in Estonian medical students with sleep problems. Depress Anxiety 2006; 23 (04) 250-256
• 49 Wild CJ, Nichols ES, Battista ME, Stojanoski B, Owen AM. Dissociable effects of self-reported daily sleep duration on high-level cognitive abilities. Sleep 2018; 41 (12) zsy182
• 50 Mirghani HO, Mohammed OS, Almurtadha YM, Ahmed MS. Good sleep quality is associated with better academic performance among Sudanese medical students. BMC Res Notes 2015; 8: 706
• 51 Bahammam AS, Alaseem AM, Alzakri AA, Almeneessier AS, Sharif MM. The relationship between sleep and wake habits and academic performance in medical students: a cross-sectional study. BMC Med Educ 2012; 12: 61
• 52 Hagewoud R, Whitcomb SN, Heeringa AN, Havekes R, Koolhaas JM, Meerlo P. A time for learning and a time for sleep: the effect of sleep deprivation on contextual fear conditioning at different times of the day. Sleep 2010; 33 (10) 1315-1322
• 53 Ferguson BA, Shoff HW, McGowan JE, Huecker MR. Remember the Drive Home? An Assessment of Emergency Providers' Sleep Deficit. Emerg Med Int 2018; 2018: 4501679
• 54 Choshen-Hillel S, Ishqer A, Mahameed F. et al. Acute and chronic sleep deprivation in residents: Cognition and stress biomarkers. Med Educ 2021; 55 (02) 174-184