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Year : 2020  |  Volume : 22  |  Issue : 2  |  Page : 86-92

Prevalence and pattern of sleep disorder among final year medical students in a teaching hospital in sub-Saharan Africa

1 Department of Internal Medicine, College of Health Sciences, University of Jos/Jos University Teaching Hospital, Jos Plateau State, Nigeria
2 Department of Psychiatry, College of Medicine, University of Lagos/Lagos University Teaching Hospital, Lagos, Nigeria

Date of Submission27-Oct-2019
Date of Decision13-May-2020
Date of Acceptance18-May-2020
Date of Web Publication11-Sep-2020

Correspondence Address:
Dr. O G Osaigbovo
Department of Internal Medicine, College of Health Sciences, University of Jos/Jos University Teaching Hospital, Jos Plateau State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jomt.jomt_37_19

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Background: Sleep is a very important physiologic process which is necessary to maintain a state of well-being. Apart from causing insomnia and hypersomnolence, sleep disorder has been shown to be associated with impairment of performance, vigilance, attention, concentration, and memory. Methods: This was a cross-sectional, questionnaire-based, observational study that was conducted from September to November 2017 on final year medical students of the University of Jos, Plateau State, North Central Nigeria. Results: One hundred and fifty-eight questionnaires were distributed with a total of 141 respondents. Their ages ranged from 23 to 46 years with a mean of 27.0 ±2.9 years. Forty-seven (33.3%) were females and 94 (66.7%) males giving a ratio of 1: 2. The female respondents had a mean age of 25.9 ±1.4 years compared to the male respondents 27.5 ±3.3 years. Sixty-four (48.2%) of the students had sleep disorder with narcolepsy as the commonest in over a quarter of respondents. Significant predictors of sleep disorders were male sex and obesity. Conclusion: Sleep disorder is common in final year medical students. There is a need to identify this disorder in these students in order to institute measures that will ameliorate its health consequences in these future healthcare leaders in sub-Saharan Africa.

Keywords: Disorder, medical, sleep, students

How to cite this article:
Osaigbovo O G, Ogbolu E R, Okeahialam B N. Prevalence and pattern of sleep disorder among final year medical students in a teaching hospital in sub-Saharan Africa. J Med Trop 2020;22:86-92

How to cite this URL:
Osaigbovo O G, Ogbolu E R, Okeahialam B N. Prevalence and pattern of sleep disorder among final year medical students in a teaching hospital in sub-Saharan Africa. J Med Trop [serial online] 2020 [cited 2021 Apr 22];22:86-92. Available from:

  Introduction Top

Sleep is an important physiological process, the function of which has remained the greatest biological mystery of all time. Its quality correlates strongly with the psychological, physical health, and other measures of well-being.[1] Sleep pattern varies with age, occupational demands, physiological, and psychosocial characteristics; it is also affected by psychiatric and physical illness.[2] Sleep deprivation causes sleepiness and impairment of performance, vigilance, attention, concentration, and memory. It also results in some metabolic, hormonal, and immunologic effects resulting in immune suppression that can manifest in a variety of ways. Deprivation of sleep with its attendant consequences have either been largely misunderstood or ignored

One-third of adult population is known to have some form of sleep disorder. [3] Generally, it has been observed that a sizeable proportion of students experience poor quality sleep and this may be related to academic stress.[4]

Irregular sleep schedules,[5] fatigue,[5] and co-morbid physical or psychological conditions[6] are associated with poor sleep quality, while poor sleep quality also predisposes to the use of stimulants, alcohol, and sedatives with attendant consequences.

The objective of this study is therefore to determine the prevalence and pattern of sleep disorder among final year medical students and the associated factors. This is necessary as research on sleep quality among student populations in our environment is scanty and a better understanding of the etiology/risk factors of sleep problems in medical trainees is essential in order to improve the quality of medical students’ and subsequently doctors‘ lives.

  Materials and methods Top

This was a cross-sectional, questionnaire-based study carried out over three months on final year medical students of the University of Jos, Plateau State in North Central Nigeria. The subjects were given a brief description of the study and its objectives and informed that they were at liberty to be part of the study or decline without negative consequence. Subsequently all consecutive consenting subjects were recruited for the study.

Ethical approval was obtained from the ethics committee of Jos University Teaching Hospital (JUTH) and confidentiality maintained by anonymizing the data and coding information obtained and storing them in password protected files. Informed written consents were obtained, following which a general and sociodemographic questionnaire, the SLEEP-50, and Epworth daytime sleepiness scales[7],[8] were administered (supervised self-administration). They were distributed to the students during mid-semester in their break times, and participation was voluntary, anonymous, and unpaid.

Hypertension: Blood pressure (an average of three measurements used) was recorded at baseline with standard accoson mercury sphygmomanometer. A cut off of ≥140/90 mmHg, a history of hypertension or use of antihypertensive drug were regarded as indicators of hypertension.

Fasting blood glucose was assessed through a thumb prick with a lancet under an aseptic procedure to obtain a drop of blood and glucose level was estimated using an ACCUCHECK glucometer, with results obtained within 12 seconds.

SLEEP-50 is a self-administered tool and consists of nine subscales for detecting sleep disorders and complaints; (a) sleep apnea, (b) insomnia, (c) narcolepsy, (d) restless leg/periodic leg movement disorder, (e) circadian rhythm sleep disorder, (f) sleep walking, (g) nightmares, (h) factors influencing sleep, and (i) the impact of sleep complaints on daily functioning.[7] Epworth Daytime Sleepiness Scale (EDSS);[8] measures daytime sleepiness and can be helpful in diagnosing sleep disorders [Figure 1].
Figure 1: Assessment of study subject’s sleepiness using Epworth sleepiness scale.

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Data, collected by the researchers with the assistance of trained research assistants, were analyzed using the Statistical Package for Social Sciences applying Chi-square tests, logistic regression, means and frequencies (SPSS, Chicago, Illinois, USA), version 17.0.[9] Statistical significance was set at P < 0.05.

  Results Top

A total of 158 questionnaires were distributed; 141 were eventually returned completed with a participation rate of 89%. The age range of the students was 23 to 46 years with a mean of 27.0 ± 2.9 years. They comprised of 47 (33.3%) females and 94 (66.7%) males giving a ratio of 1: 2. The mean age of the female respondents was 25.9 ± 1.4 years while the males had a mean of 27.5 ± 3.3 years giving a difference that attained statistical significance (P = 0.001).

A significantly higher number of males were also hypertensive (P = 0.017). Regular alcohol consumption was observed in 16/141 (11.3%) of the students out of which 14/94 (14.9%) were males and 2/47 (4.3%) were females. The difference was not statistically significant.

Those that were married were in the minority (3.5%). Similarly, only one student (0.7%) had diabetes but 49 of them (34.8%) were hypertensive.

Eighty-eight (62.4%) subjects (males n = 55) said they had emotional relationships with the opposite gender, with no statistically significant difference across gender while 40 (28.4%) took afternoon naps (males n = 28), P = 0.597. Only one subject (male) had diabetes. Fifty-four (38.3%) considered their sleep duration to be normal (males n = 38), and twenty-five (17.3%) reported using stimulants (male, n = 13), P = 0.086. Forty-two (29.8%) reported snoring (males n = 31), P = 0.241.

Additionally, anthropometric measures differed between genders and were mostly statistically significant except for BMI; the mean BMI was 24.4 ± 4kg/m2 with no statistically significant difference between genders. The mean fasting plasma glucose was 5.16 ±0.7mmol/L; male 5.14 ± 0.8mmol/L, female 5.2 ±0.5mmol/L, with no statistical significance. However, systolic and diastolic blood pressures were significantly higher in males. The rest of the baseline and anthropometric characteristics of the subjects are captured in [Table 1].
Table 1: Baseline and anthropometric characteristics of the subjects

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There was a positive association between sleep disorder and male gender, weight, height, abnormal body mass index, waist circumference, waist hip ratio, and neck circumference [Table 2].
Table 2: Demographic and clinical characteristics stratified by sleep disorder

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A total of 64 (48.2%) of the students had sleep disorder. As shown in [Table 3], 36 (25.4%) of the students had Narcolepsy and this was the commonest sleep disorder in this study population.
Table 3: Sleep disorders in subjects

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There was no sleep disorder in 73 (51.8%) of the study population. The other types of sleep disorders identified are shown in [Table 3].

The study showed that male gender, high body mass index, and waist hip ratio predicted sleep disorder as shown in [Table 4].
Table 4: Logistic regression of sleep disorder

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  Discussion Top

The respondents in this study were young, aged between 23 and 46 years which is different from findings by Ogbolu et al [10] in Lagos perhaps attributable to different study populations. Majority of the respondents 136 (96.5%) were single, which is perhaps not surprising among a student population. It was also seen that only 54 (38.3%) of the students had a normal sleeping duration of 7–9 hours[11] within a 24 hour period, with only one reporting the use of sleeping pills. This suggests that the shorter sleep duration among most subjects may be some form of intentional sleep deprivation, perhaps to read at night as is common among medical students. This may also be related to the finding that only 40 (28.4%) volunteered taking afternoon naps occasionally and that some of them (17.3%) used stimulants to keep awake.

Studies in different parts of the world have shown that sleep disorders are common in medical students.[12] The result of this study has revealed that the prevalence of sleep disorder among this population of students was 48.2% which is in contrast with 25% reported by Jain et al.[13] in India, and 36.6% reported by Abdulghani et al.[14] in Saudi Arabia. The reason for the high prevalence in our study could be because our study was on students in their final year class in the medical school when students have more academic workload to grapple with. It is well-known that there is a relationship between academic stress and good quality sleep,[4] whereas the other studies were on students in their early years in the medical school with less academic workload. Our study further revealed that the most prevalent type of sleep disorder in the study population was narcolepsy which was found in 36 (25.4%) of the respondents. This was followed successively by nightmares in 30 (21.1%), hypersomnia 18 (12.7%), insomnia 14(9.9%), circadian rhythm sleep disorder 10 (7%), restless leg syndrome 5 (3.5%), obstructive sleep apnea 4 (2.8), and sleep walking in 1 (0.7%) of the respondents. Our finding was in contrast with what was reported by Jain et al.[13] in India; narcolepsy (18%) obstructive sleep apnea (11%), circadian rhythm sleep disorder (6%), insomnia (4%) nightmares (3%) and sleep walking (1%). The reason for this difference could be from the differences in the age range of the study population as the prevalence of sleep disorder increases with age[15] and the fact that our study population is also exposed to more academic stress as compared to the study population reported by Jain et al.[13]. In a study of insomnia among psychiatric out-patients in Lagos Nigeria, Ogbolu et al.[10] reported a prevalence of 20.1%. The reason for the high prevalence of insomnia in this study compared to ours could be from the different populations studied and the fact that insomnia was found mostly in subjects with major depression in their study, as there is a link between depression and insomnia[16] whereas depression was not a feature in our respondents.

Among those with sleep disorders, most of them had only one of the subtypes of sleep disorder (27%), while 13.5% had 2 subtypes of sleep disorder and 8.5% had 3 or more subtypes of sleep disorder. It is interesting to note that sleep disorder was significantly more in the male subject, similar to findings by Krishnan et al.[17] This is in contrast to what was reported in some studies where there was no gender difference in sleep disorder[18] and findings in other studies where sleep disorder was found to be commoner in women than men.[19] The reason for the finding in our study could be because of the lower population of female respondents. It is a well-known fact that menstrual cycles and other hormonal changes in women can affect sleep architecture.[17]

The mean sleeping duration in this study was 6:39 ±1.2 hours. This observation of shortened sleep duration is similar to what was reported by Surani et al.[20] in Pakistan, and Bricks et al. [21] Furthermore, 90 (63.8%) of our subjects were able to correctly rate the adequacy/inadequacy of their sleep in relation to the recommended daily requirement [11] but they didn’t understand the need to maintain a good sleep hygiene. This is similar to finding by Azad et al.[12] who reported that medical trainees had poor knowledge of sleep. Thus, even though 63.8% of our respondents recognized that they were either sleeping adequately or otherwise, this knowledge did not reflect in the prevalence of sleep disorder. This is likely because the students either did not understand the negative consequences of sleep disorders or deliberately ignored such, perhaps due to the huge academic workload and stress they had to grapple with. There is a direct relationship between stress and sleep disorders [4],[14]

In our study, we also found that 42 (29.8%) of our subjects snore regularly during sleep. This finding is less that the 50% reported by Akintunde et al.[22] at Oshogbo, among hypertensive Nigerians and 31.6% reported by Adewole et al.[23] among adult Nigerians. The reason for these variations could be from the differences in population, degree of obesity, and race studied. Our study also revealed that snoring was commoner in men compared to the women in keeping with earlier reports that women are less likely to report symptoms of loud snoring, apnea, and nocturnal gasping. [24]

None of our respondents had bruxism in the last 4 weeks prior to being recruited into the study. Although the prevalence of bruxism in the general population has been reported to range from 5% to 22%,[25] university students are thought to have a higher prevalence of sleep bruxism in the range of 31.8%, a reflection of the degree of stress they are exposed to in an academic environment.[25] This variation from our study could be from the different time frames considered in these studies (1 month vs 6 months) or the fact that bruxism is not a common disorder in Nigerians. However, further studies in this regard will be necessary to explain this finding.Twenty five (17.3%) of the respondents admitted to regular use of stimulants to suppress sleep and enable them concentrate better during reading. Stimulants used include; coffee, energy drink, Lipton tea, Coca-Cola, and glucose. This is in contrast with 11% reported by Fallah et al.[26] it is however noteworthy that the types of stimulants volunteered in our study were quite different from what was reported in theirs, most probably related to personal choice or availability.

Using the sleep-50 tool, 18 (12.7%) of the respondents had hypersomnia, while with the Epworth sleeping assessment tool, 52.5% had enough sleep, 35.2% of the respondents were sleepy, 11.3% were very sleepy and 0.7% was dangerously sleepy. The prevalence of hypersomnia in our study is higher than the 4 to 6% reported in the general population.[27] The reason for this high prevalence could be from nocturnal sleep deprivation from stimulants use and subsequent daytime hypersomnolence.

Central obesity is associated with increased upper airway mechanical resistance and a decreased compensatory neuromuscular response. In our study we found an association between measures of obesity (weight, waist hip ratio, abnormal body mass index, and neck circumference) and sleep disorder. This is similar to report by Awopeju et al.[28] at Ile Ife south western Nigeria. Research has shown that waist hip ratio is the most reliable correlate of sleep disorder (obstructive sleep apnea) in both sexes but that neck circumference was an independent risk factor for the male gender.[29]

In this study, male gender and being obese were seen to be independent predictors of sleep disorders.

In conclusion sleep disorders were comparatively very common among final year medical students and the knowledge of the presence/absence of poor sleep in these students did not reflect in their sleep habits. The finding that narcolepsy was the commonest type of sleep disorder identified, and that those with sleep disorders had comparatively higher weight and BMI indicate the need for education on sleep hygiene and the complications of sleep disorder among medical schools, which we therefore recommend. We recommend that such education should be in the early years and should include the importance of improved sleep to physical and mental health.

There is also a case for the possible use of anthropometric measures to predict the risk of sleep disorders in this category of subjects and even the general population.

Optimizing sleep quality will ultimately improve the wellness of the future health care professionals and subsequently improve the health care delivery system.

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Conflicts of interest

There are no conflicts of interest.

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]


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