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ORIGINAL ARTICLE
Year : 2011  |  Volume : 5  |  Issue : 1  |  Page : 1-5

Prevalence and correlates of poor sleep quality among medical students at a Nigerian university


Department of Clinical Services, Federal Psychiatric Hospital, Uselu, Benin City, Nigeria

Date of Web Publication24-Aug-2011

Correspondence Address:
Bawo O James
Federal Psychiatric Hospital, P.M.B 1108, Benin City, Edo State
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0331-3131.84218

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   Abstract 

Objective : This study aimed to determine the prevalence and factors associated with poor sleep quality among medical students at a Nigerian university.
Materials and Methods : In a cross sectional survey, the sleep quality of students (n=255) was assessed using the Pittsburgh Sleep Quality Index (PSQI). In addition to obtaining sociodemographic data, history of adverse childhood experiences and drug use, measures assessing daytime sleepiness, fatigue and psychiatric morbidity were also administered.
Results : Almost a third (32.5%) of medical students reported poor quality sleep. The presence of a chronic illness (OR: 5.10, 95% CI: 1.53-17.11, P<0.02), adverse childhood experience (OR: 1.73, 95% CI: 0.98-3.02, P<0.05) and irregular sleep schedule (OR: 4.78, 95% CI: 2.65-3.02, P<0.01) significantly predicted poor sleep quality.
Conclusion: Poor quality of sleep is common among medical students, and is associated with predisposing and several modifiable factors. Strategies to improve sleep quality are suggested.

Keywords: Co-morbid psychoactive substance use, fatigue, irregular sleep schedules, sleep quality


How to cite this article:
James BO, Omoaregba JO, Igberase OO. Prevalence and correlates of poor sleep quality among medical students at a Nigerian university. Ann Nigerian Med 2011;5:1-5

How to cite this URL:
James BO, Omoaregba JO, Igberase OO. Prevalence and correlates of poor sleep quality among medical students at a Nigerian university. Ann Nigerian Med [serial online] 2011 [cited 2019 Jul 17];5:1-5. Available from: http://www.anmjournal.com/text.asp?2011/5/1/1/84218


   Introduction Top


Sleep provides reparative and restorative bodily functions. [1] The subjective quality of sleep among various populations has become a focus of research in recent times. Using diverse assessment tools, aetiological and associated factors of poor sleep quality have been reported.

Generally, it has been observed that a sizeable proportion of students experience poor quality sleep. [2],[3],[4],[5] Among medical students, sleep quality is poorer still, due to the rigorous training program. [6] Poor sleep quality impairs academic performance [2],[7] and is associated with an increased risk of psychological morbidity and burnout. [8] Furthermore, irregular sleep schedules, [8] psychoactive substance use, [9] fatigue [10] and co-morbid physical or psychological conditions [11],[12] are associated with poor sleep quality. Recent evidence for the predisposing risk of adverse childhood experiences on sleep quality has been reported. [13]

In Nigeria, research on sleep quality among student populations is scanty. [2],[14] Among undergraduate medical students as a specific subgroup, none has been conducted to the knowledge of the authors. We considered a study on this subject area among medical students in Nigeria relevant for the following reasons; first, frequent industrial actions (strikes) among university lecturers in recent times have resulted in longer and unpredictable training periods. Secondly, government funding is minimal and students may grapple with financial constraints, overcrowded classrooms, poor or non-existent teaching aids as well as scarce hostel facilities. [15] We hypothesized that in the light of the aforementioned constraints, Nigerian medical students may likely report poorer sleep quality compared to their counterparts from developed countries reported in the literature. As a developing country with a dire need for medical personnel, strategies to improve the quantity and more importantly the quality of future medical doctors are welcome. In this study, we aimed to determine the prevalence of poor sleep quality among medical students in the penultimate year of their six-year program at a Nigerian university; as well as identify its associated correlates.


   Materials and Methods Top


Study setting and participants

This study was conducted at the Federal Psychiatric Hospital, Benin City in March, 2010. Students of the Igbinedion University, Okada, Edo State, Nigeria, in the fifth year of their six-year undergraduate medical program undertake a mandatory 10-week clerkship in psychiatry at this hospital.

Ethical clearance

The study protocol was reviewed and approved by the Research and Ethics committee of the Federal Psychiatric Hospital, Benin City

Procedure

The nature and purpose of the survey was explained to the students during a lecture session. Confidentiality was assured and students who consented to participate were given questionnaires which were to be returned at another lecture session within the week. The questionnaire was pretested among ten (10) medical students who were excluded from the main study and was found to be clear and well understood.

Measures

Socio-demographic questionnaire

A socio-demographic questionnaire was designed by the authors for the purpose of this study. It elicited variables like age, gender, history of chronic physical illness, frequency of psychoactive substance use and concurrent use of sleep medication with dichotomous 'yes-no' responses. Frequency of psychoactive substance use was identified on a 5-point Likert scale (not at all, rarely, mild, moderate and heavy)

Pittsburgh sleep quality index (PSQI)

The PSQI [16] is a standardized 24-item self-rated questionnaire designed to measure sleep quality as well as alert physicians on the need to further evaluate individuals with symptoms of sleep problems. The questionnaire generates a global score ranging from 0 to 21, with higher scores indicative of poorer subjective sleep quality. The PSQI has good psychometric properties and has been validated among student populations in Nigeria. [14] As in other populations, a cut-off score above 5 was indicative of poor sleep quality among students in Nigeria.

Family related adverse childhood experiences (ACE)

An adapted version of an ACE questionnaire [13],[17],[18],[19] was used. A detailed illustration for each statement was provided to improve clarity. [19] Respondents were to indicate with dichotomous 'yes-no' answers if they experienced these situations before the age of 16; parental divorce, long term financial conflicts, serious verbal conflicts in the family, frequent fear of a family member, severe illness of a family member, alcohol or substance use problems of a family member, death of a parent or loved one.

Epworth sleepiness scale (ESS)

The ESS is a self-administered 8-item questionnaire. It provides a measure of an individual's general level of daytime sleepiness, or their average sleep propensity in daily life. Responses are recorded on a 4-point Likert scale, with a possible score range between 0 and 24. A score of 11 and above is generally agreed as indicative of sleepiness. The ESS has good psychometric properties [20] and has been used previously in this environment. [2],[21]

Fatigue severity scale (FSS) of sleep disorders


The FSS questionnaire is comprised of nine statements. It enquires about the impact of fatigue on individual functioning in the preceding week. Individuals rate their level of agreement or disagreement to nine statements on a 7-point Likert scale. In general, a score of 36 and above (out of a maximum of 63) indicates the presence of significant fatigue. The FSS has good psychometric properties [22] and has been used previously in student populations. [8]

12-item General health questionnaire (GHQ-12)


The GHQ-12 [23] is a 12-item self-rated questionnaire useful in the quick assessment of general psychopathology in adult populations. The GHQ-12 has been validated in Nigerians, [24] and a cut-off score of 3 and above is indicative of probable psychiatric morbidity

Data Analysis

Data were analyzed using the Statistical Package for Social Sciences (SPSS, Chicago IL) version 16. Descriptive statistics were used to summarize the data. The chi-square (Fisher's exact tests where necessary) and independent t tests were used to analyze categorical and continuous data respectively. For the ease of analysis, the frequency of substance use was grouped into none/infrequent use (not at all, rarely, mild) and frequent use (moderate, heavy). The relationship between global PSQI scores and scores on the FSS, ACE, GHQ-12, ESS was conducted using the Pearson correlation co-efficient. We entered variables significantly associated with poor sleep quality into a binary logistic regression model to determine predictors of poor sleep quality (PSQI >5). Level of significance was set a priori at P<0.05.


   Results Top


A total of 280 questionnaires were distributed, 261 were returned, (participation rate of 93%). Of those returned, 6 were incompletely filled and were not analyzable. Two hundred and fifty five (255) questionnaires analyzed. The age range of the whole sample was between 19 and 40 years. The mean age (SD) of the group was 24.45 (2.32) years. There was a slightly higher proportion of the female gender (51%). Medical students in the sample, who were married, were in the minority (3.9%). Similarly, a small proportion of the students had a chronic physical illness e.g. diabetes, asthma, hypertension (5.1%). Only eight students (3.1%), had previously been diagnosed with a sleep disorder and were currently or previously on sleep medications at the time of the study.

Eighty three students (32.5%) reported poor sleep quality. The presence of a chronic physical illness (P<0.01), use of sleep medications (P<0.002) and irregular sleep schedules (P<0.0001) were significantly associated with poor sleep quality. However, there were no statistically significant differences between good and poor sleep quality in terms of gender (P=0.53), marital status (P=0.86) and a prior diagnosis of a sleep disorder (P=0.12). Furthermore, frequent alcohol use (P=0.04), but not caffeine (P=0.41) nor cannabis/nicotine (P=0.25) was significantly associated with poor quality sleep. [Table 1].
Table 1: Comparison of categorical variables with sleep quality

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Students with poor sleep quality had significantly higher numbers of family related ACEs (t=-3.343, P<0.01) and FSS scores (t=-2.723, P<0.01). This group of patients also had higher but statistically insignificant mean scores in terms of age (t=-1.29, P=0.90), ESS scores (t=-0.977, P=0.34) and GHQ-12 scores (t=-0.381, P=0.710). Pearson's correlation analysis showed a statistically significant and a positive though moderate correlation between global PSQI score and number of family related ACEs (r=0.184, P<0.003), FSS scores (r=0.207, P<0.001), and GHQ-12 scores (r=0.143, P<0.023), but not ESS scores (r=0.080, P=0.202). Statistically significant variables were entered into a binary logistic regression model, with good/poor sleep quality as the dependent variable. The presence of a chronic physical illness (P<0.02), >1 night/week of irregular sleep (P<0.01), and having at least one family related ACEs (P<0.05) were significant predictors of poor sleep quality in this sample [Table 2].
Table 2: Predictors of poor sleep quality

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   Discussion Top


This is the first study to specifically examine the prevalence of poor sleep quality and its associated factors among Nigerian medical students. In Nigeria, undergraduate medical training is as rigorous as in most other countries of the world. Training facilities are sometimes overstretched by the number of trainees. The sample of medical students who participated in this study undertake clinical rotations in most of their specialties at hospital centres sometimes located far from where they reside.

Though a sizable proportion of students reported poor quality sleep in our study, it was well within rates (11.5-60%) reported in this and other environments. [2],[8],[25] The fact that trainees undergo more strenuous schedules as they progress in their medical program, may account for the high proportion of medical students in their penultimate year experiencing poor sleep quality. However, studying in sometimes unpredictable and more strenuous academic environment did not result in a higher prevalence of poor sleep quality using the PSQI compared to similar studies in other environments using a similar methodology. Expectedly, the minority who had a chronic physical illness and used sleep medications were significantly more likely to report poorer sleep quality. Medical students may erroneously resort first, to the use of medications to manage sleep problems or misuse sleep medications to manage conditions like anxiety disorders and develop poor quality sleep. Psychoactive substance use is common among medical students. [26] Here we observed that the frequent use of alcohol was associated with poor quality sleep and a similar finding was reported in an earlier study. [9] Furthermore, we observed a significant relationship between poor sleep quality and irregular bed time schedules. Though the validity of the sleep schedules recorded might have been affected by recall bias, nonetheless, it replicates similar findings among Taiwanese students. [8]

The FSS, GHQ-12 score as well as higher numbers of family related ACEs were significantly correlated with higher global PSQI scores. Fatigue as measured by the FSS scale may be an indirect measure of physical over-activity. In the population surveyed, this relationship was not unexpected, seeing that the students receive most of their clinical training at facilities far from where they reside. The significant correlation between GHQ-12 scores and global PSQI should be interpreted with some caution because; a component of the 12-item GHQ also assesses sleep impairment, and may affect the reliability of the correlation.

The presence of a physical illness, number of adverse childhood experiences (ACE) and irregular sleep were observed to independently predict poor sleep quality. Concerning the relationship between poor sleep quality and ACEs, the design of this study limits interpretation or inference as to causality. However, it does appear that ACEs may set in process abnormal physiological processes that increase the risk for poor sleep quality as well as other physical or psychological illnesses. [13],[17]

Poor sleep quality impairs academic performance, [2],[7] and medical educators keen to improve students' academic performance should give priority to highlighting the deleterious effects of these factors. Among the factors identified in this study, irregular sleep schedules are easily modifiable. Approaches may be targeted at the individuals themselves in the form of sleep hygiene education, or at eliminating environmental factors like extended lecture schedules, irregular examination times and poor living facilities. On the other hand, it may be argued that some of these identified factors may actually be ways in which medical students cope albeit maladaptive, with sleep problems. Notwithstanding, strategies aimed at improving the quality of sleep among medical students are beneficial not only to the students themselves, but to the general population who will benefit from the qualitative care they will offer in the near future.

This study has some limitations. First, generalization of our results would be difficult, since we conducted this study at a single centre. Secondly, our study design does not allow for inferences on cause and effect. Thirdly, irregular sleep schedule was obtained by self report, which is prone to recall bias. Lastly, we did not factor anthropometric measures such as the body mass index (BMI) which may be important covariates.


   Conclusion Top


Poor sleep quality is common among Nigerian medical students. Chronic physical illness, the presence of adverse childhood experiences and irregular sleep patterns were significant predictors. Education on sleep hygiene techniques and its application would be beneficial in this student population.

 
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    Tables

  [Table 1], [Table 2]


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