Prevalence of Sleep Disorders among Medical Students Research Paper

Introduction

Sleep denotes a naturally happening situation of the body and mind typified by changed perception, moderately hampered sensory action, inhibition of almost every voluntary muscle, as well as decreased interrelations with the environment. ¹ It differs from wakefulness through a reduced capacity to respond to stimuli, although it is simply overturned than the situation of comatose. While one is asleep, many processes in the body are in anabolic condition, assisting in the regeneration of the nervous, muscular, immune, and skeletal systems.

Human beings might suffer a range of sleep disorders, which include narcolepsy, insomnia, sleep apnea, circadian rhythm sleep disorders, and hypersomnia. Human beings are supposed to spend approximately a third of their lives asleep; nevertheless, some do not as they tend to overwork themselves, which results in different sleep disorders. ² Though its significance is yet to be completely expounded, sleep is a fundamental necessity of every living creature, encompassing people, and its absence or inadequacy carries severe psychological problems.

In physiology, sleep is categorized into a couple of broad groups; that is, rapid eye movement (REM) and non-rapid eye movement (NREM/non-REM). ³ NREM and REM vary greatly to the extent that physiologists term them as distinct behavioral conditions. Nightmares and dreams arise in the course of REM sleep as it is linked to desynchronized and quick brain waves, deferral of homeostasis, and failure of muscular tonus. On the contrary, non-REM is associated with deep sleep (muscular paralysis).

Sleeping happens in sequences of about ninety minutes each, and such an interval is referred to as the ultradian sleep cycle. ⁴ In this regard, sleep occurs in cycles of REM and non-REM, typically in that order and mainly four or five of such every night.

The American Academy of Sleep Medicine splits non-REM into 3 phases that encompass N1, N2, and N3, where the final one is as well referred to as delta sleep; the entire sequence progresses from N1, N2, N3, to REM. ⁵ Rapid eye movement sleep takes place as an individual goes back to phase 2 or 1 of non-REM sleep. Rapid eye movement sleep normally stays for long toward the end of the sleeping time when judged against the early segment (a few hours after falling asleep at night). The highest share of deep sleep (phase N3 of non-REM) occurs early in the night whereas the amount of REM sleep rises in the final 2 sequences prior to natural awakening.

The major physiological pointers of sleep encompass electroencephalogram, electromyogram, and electrooculogram. ⁶ Sleep boosts the sensory threshold; that is, when a person is sleeping, he/she perceives lesser stimuli. Nonetheless, such a person can react to loud noises, in addition to other salient sensory occurrences. ⁷ Sleep disorders have been established to affect many millions of individuals across the globe hence the need for effective interventions.

Background and Systematic Literature Review

A few researchers have centered on sleeping problems amid the Saudi populace and disclosed a high prevalence of the disorders. ⁸ Such facts show a great requirement for enhanced future research internationally. Currently, there have been inadequate studies regarding the incidence of sleep disorders in the Kingdom of Saudi Arabia. Studies that seek to screen for sleep practices and the different sleep disorders assert that the incidence of excessive daytime sleepiness (EDS) is high in Saudi Arabia (about 40%) in conjunction with a high score on the Epworth Sleepiness Scale (ESS) particularly when judged against other western populace. ⁴⁷

Moreover, research implies that the occurrence of the problem along with EDS is noteworthy. ⁹ It has also been found that the occurrence of sleep disorders is particularly high amid medical students. ^{32, 35, 44} The quality of life represents a critical outcome aspect in the selection and evaluation of treatment options for sleep disorders. Outcomes regarding sleep disorders that have been established, and insomnia, restless legs, sleep apnea, and narcolepsy have constantly indicated poor quality of life when judged against population norms before treatment, predominantly in the dimensions associated with exhaustion, energy, and sleep. ¹⁰

Even after treatment, quality of life assessment might or may not advance to the extent of population standards, denoting that the presently available approaches could fail to reverse the impact of the widespread sleep disorders completely.

Sleep is a physiological progression that may be influenced by a broad scope of disorders. ¹¹ Though such disorders have been found to affect a high number of people internationally, encompassing medical students, they are inadequately recognized. ¹² Some studies indicate that sleep disorders have been neglected by both medical personnel, in addition to the public. ²⁵ In particular, sleep marks a crucial active physiological progression that has for long been deemed a dormant portion of daily life. ¹³ Any phase (whether non-REM or REM) is subject to disruption, which could result in an extensive array of disorders that result in severe effects in people’s daily operations and their psychological and physical health in numerous approaches.

Circadian and sleep disruptions and disorders affect many people in the United States across every demographic grouping. An approximated 25% to 30% of the entire adults and a comparable proportion of adolescents and children are negatively influenced by a reduction in sleep health, which is a confirmed cause of death, morbidity, and disability. ¹⁴ Over 90 circadian and sleep problems have been recognized and explained in nosological networks, and the most prevalent ones are insomnia, shift work syndrome, sleep apnea, and narcolepsy. ^{4, 39}

Regardless of such occurrences, sleep medication is deemed an imperceptible, unnoticed, or under-recognized subdivision of medicine; leave alone the extant disorders, particularly amid the public. In Saudi Arabia, just a small percentage of studies have been undertaken to tackle such an epidemiological problem, and the fundamental facts and rates are exceedingly startling. Ohayon discussed the incidence of different sleep disorders and problems amid health professionals and affirmed that over and above their prevalence, they are inadequately studied. ⁴¹

Primary Health Care professionals in Riyadh do not sufficiently comprehend the significance and influence of insomnia and other sleep disorders, attributable to their poor identification of such occurrences. ¹⁶ Furthermore, recent research carried out amid medical learners to evaluate their understanding of sleep medicine has been remarkable to establish that most of them have poor awareness of the topic and notably reflects the weak state of education in the sector amid both the learners and other people. This is greatly alarming because every accessible local community-anchored research discloses a high level of sleep-associated problems, symptoms, and unfavorable episodes. ¹⁷

On the same note, insomnia acts as an exceedingly devastating sleep disorder that has been established to affect approximately 29 percent of the residents of Saudi Arabia with females suffering a greater effect than males. ¹⁸ Attributable to the above-stated facts, sleep disorders are indeed significant epidemiological problems that require being tackled and expatiated in detail.

Currently, there is no extensive-scale survey for the evaluation of a full range of sleep disorders across every demographic grouping. ¹⁹ In this regard, it is vital to carry out such a survey while considering gender, age, socio-economic dissimilarities, and race. ²⁰

The establishment of the influence of sleep-associated disorders on dissimilar facets of people’s practices, that is, economic and social characteristics, is imperative to expedite the establishment of successful endeavors to determine such a concern solemnly through the improvement of health professionals’ identification, diagnosis, and management of the disorders. The existing literature presents scores of studies regarding dissimilar sleep disorders exclusively or merged in community-anchored or population-founded surveys. ²¹ In the US, an approximated fifty to seventy million residents chronically experience circadian rhythm or sleep disorders.

Studies have established that sleep disorders associated with breathing, encompassing sleep apnea, have an effect on over 15 percent of the populace, and results in daytime sleepiness and connected dangers (for instance, drowsy driving), high blood pressure, and cognitive problems, and are linked to metabolic syndrome as well as a high risk of coronary failure, stroke, and death. In young people, sleep disorders are associated with metabolic and cardiovascular risk aspects, attention-associated behavioral issues, and poor performance at school. ²² Restless legs syndrome distresses over 5 percent of grown-ups across the globe and leads to lack of sleep and consequent drowsiness during the day. Chronic insomnia affects almost 20 percent of grown-ups internationally and is a risk aspect for depression, drug abuse, and disordered waking function. Co-morbid physical (for example, cardiopulmonary, unending pain) and psychological (such as distress) problems might be intensified by insomnia.

Rapid eye movement sleep conduct problem affects less than one percent of grown-ups across the globe and might make patients to cause injuries to themselves or other people when sleeping. ²³ Current studies link this disorder with an enhanced likelihood of Parkinson’s disease, in addition to other neurodegenerative illnesses. The effect of narcolepsy, as well as other types of hypersomnia, is felt in about 2000 people across Saudi Arabia hence causing disordered sleep and having too much sleep during the day, consequently decreasing the excellence of life and performance at the place of work or learning institution. ²⁴

Chronic circadian interruptions and problems, for instance, shift work issues and tardy sleep time disorder, considerably stimulate safety, healthiness, and welfare challenges, for instance, high possibility of cardiovascular illness, cerebrovascular sickness, diabetes, gastrointestinal disease, colorectal cancer, prostate cancer, breast cancer, car accidents, and trouble abiding by work and school programs. ²⁵ Though population incidence approximations of particular circadian interruptions and disorders are generally not available, about 1 out of every 5 employees in the United States is exposed to shift-work plans. ²⁵

Studies have been carried out in Spain to concentrate on the full range of sleep disorders in the grown-up population and established that a huge proportion of the problem amid the residents is akin to the one noted in other nations. For instance, it has been affirmed that 11 percent of the population suffer from insomnia, which is highly prevalent in females, older, and unemployed people. ²⁶ Drowsiness in the course of the day has been determined to affect 12% of the population, 3% report suffering hypersomnia, and the effect of sleep paralysis and sleep attacks is uncommon. ²⁷ The studies have also found that daily snoring occurs in 12% of the population, and about 1% report respiratory pauses in the course of the night.

In Japan, the earliest countrywide population-anchored research was carried out to determine the level of sleep disorders and use of hypnotic medicine among the adult residents. In one of such studies, a high number of Japanese adults from 20 years of age was randomly chosen and assessed with the help of the Pittsburgh Sleep Quality Index. ¹⁴ In the study, the respective approximated overall incidence of insomnia, problem falling asleep, challenge sustaining sleep, poor sleep quality, and use of hypnotic medicine was 22%, 13%, 16%, 20%, and 5% in females and 17%, 9%, 13%, 18%, and 4% in males. On this note, studies have affirmed that sleep disorders and use of hypnotic medicine are widespread amid Japanese grown-ups with sociodemographic aspects established to contribute highly to the problem. ³³

On a broad perspective, research affirms that the incidence of sleeping disorders is more than 50% in the United States, about 30% in Western Europe, and 20% in Japan. ²⁸ The majority of people with sleep disorders assert that they have a negative influence on their daily operations, and family life is the highest affected in Western Europe, personal undertakings in the United States, and professional actions in Japan. Nearly 50% of the people with sleeping problems have never tried to address the disorders, and most of the respondents do not make the issue known to health professionals. ²⁹ Out of the people who have disclosed the problem to caregivers, medication prescription had been administered to nearly half of them in the United States and Western Europe and 90 percent in Japan. ¹¹

A wide pool of studies across the world has studied comprehensively the aspects that influence normal sleep. ³⁰ Sleep disorders result in multiple impacts, encompassing emotional, socioeconomic, and health factors. The occurrence of anxiety in addition to depressive symptoms denotes the most consistent psychological aspects linked to sleeping problems across dissimilar settings. ³¹ Socioeconomic factors encompassing traumatic encounters (such as being a victim of criminal activities), social undertakings (for instance, social groups), economic position (for example, financial worries), and employment (such as job satisfaction) have as well been found to contribute to the occurrence of sleep disorders. ^{10, 42} The connection involving sleeping problems and physical health has been outlined in research studies. ^{1, 10, 28}

Such aspects might function separately or jointly to influence sleep, implying the need to explain numerous issues when seeking to comprehend the inclination and determinants of sleep disorders across dissimilar population settings. This justifies the occurrence of sleep-associated disturbances at a high rate among the older adults attributable to the incidence of psychosocial and health comorbidities and the frequent application of several medications, instead of ageing per se. ³² The occurrence of sleeping problems is a major issue that is usually ignored and under-addressed by medical students and health professionals.

Sleep medication is a somewhat new field of expertise in the health care sector in Saudi Arabia. ³³ Efforts surrounding sleep medication in Saudi Arabia started at around 1995. Since its inception, the field has developed tremendously, and the level of professionals has augmented. ²¹ Nonetheless, sleep medication is still inadequately developed in the Kingdom of Saudi Arabia, especially in the sectors of medical service, education, guidance, and research. There have been inadequate researches on the topic of sleep disorders among medical students across the globe. ²⁵

A study by Foley, Monjan, Brown, and Simonsick sought to evaluate sleep patterns and different sleeping problems with the help of a standard questionnaire in random sampling of health professionals. ²³ The study established that the occurrence of extreme daytime drowsiness was high (40%) in conjunction with an elevated average score of the Epworth Sleepiness Scale particularly when judged against other western nations, implying that the incidence of sleeping problems arise with considerable sleepiness. ²³

Approximately 45% of medical students are snorers with just 5 percent being habitual ones. ³⁴ With respect to sleep apnea, it has been established to affect 6% of the female and 8% of the male adult population. 35% and 52% of male and female individuals confess experience insufficient sleep or insomnia respectively. ⁴ Signs of the restless leg syndrome, narcolepsy, and sleep paralysis have been reported by a high number of medical students. ³⁴

Most studies have concluded that sleeping problems are widespread but unidentified across the globe. Nevertheless, some studies lack objectivity in the evaluation of participants by just depending on their direct personal account. Just a few sleeping problems have been tackled solely in an effort of providing enhanced understanding and bringing such common predicaments to light and disclose the real burden. It has been found that amid the health professionals; approximately 33% of the youthful male caregivers are at high risk of obstructive sleep apnea. ³⁵ Other studies disclose considerable medical and Polysomnograph dissimilarities involving Saudi men and women with obstructive sleep apnea. The approximated incidence of narcolepsy is forty out of 100,000 Saudis whereas that of restless legs in the same population is 5%. ³⁶

Following the revelation of the reality that sleeping problems represent definite common disorders in the Kingdom of Saudi Arabia, studies have been undertaken to determine the general awareness and approach of primary medical professionals towards offering an amicable solution. ³⁷ Most of the studies have expressed poor insight and understanding of sleeping problems and their effects, in addition to a low level of referrals to sleep treatment centers. ^{36, 39}

To make the matter worse, numerous studies have disclosed an over ten-year delay between the commencement of signs and referral to sleeping problems’ treatment facilities among Saudi females with sleep apnea, which backs the affirmation that the disorders are not adequately recognized and tackled. ³⁸ The negative effects of sleeping problems on the Saudi residents have not been effectively tackled by researchers, mainly the impact on medical students.

Sleep disorders are prevalent in public, and about 30% of all adults have experienced some form of sleeping problem. ³⁹ A global study of ten nations established 33% incidence of insomnia amid health professionals. ⁴⁰ Medical students represent the biggest proportion of the general public that seems to be particularly susceptible to sleep disorders, possibly attributable to the lengthy duration and great intensity of the course, medical tasks that encompass overnight on-call operations, assignments that may be psychologically challenging, and lifestyle preferences. The recognition of the factors that result in sleep disorders amid medical students is vital if instructors and learners desire to improve the learning outcomes.

The existence of the disorders is linked to both internal and environment aspects. Biological facets, for instance, hyper-stimulation of the automatic nervous coordination might act as a prompting aspect, distressing occurrences such as tests and relationship difficulties may be precipitating occurrences, and nervousness and rumination can be propagating elements for the sleeping problems. Cognitions before sleeping, that is, active deliberation, anxiety, and making plans and analysis at night are considerably associated with insomnia.

Studies concerning sleep disorders amid junior vs. senior undergraduate medical learners are of special interest due to the known relationship involving sleep and psychological health and the fact that the academic requirements at the universities may result in significant distress. Any further undiagnosed sleeping disorders can seemingly aggravate psychological stress in the learners who have possible lasting consequences for both their personal welfare and the overall excellence of the medical industry. An extensive body of research backs the idea that quality and sufficient sleep is vital for utmost neurocognitive as well as psychomotor operations in conjunction with psychological and physical wellbeing. ⁴¹

It has been found that the four imperative attributes of sleep that influence academic performance encompasses quality, sufficiency, phase development, and regularity. ⁴¹ Since medical students have to endure a lengthy and demanding academic course prior to qualifying to operate as physicians, there is a need to assess the possibility of sleeping problems, the scope of the disorder, and whether sleep interruptions have any impact on educational performance along with the quality of life.

Numerous studies have been done to evaluate the knowledge, convictions, attitudes, and insights regarding sleep amid medical students and public and medical workers in Arab and Gulf nations. Such studies assert that the medical students understand sleeping problems as a great setback though they do not know much regarding the disorders. ^{43, 45} For instance, over half of the medical students are not aware that bruxism and sleep talking deemed sleeping problems, and just a small proportion of the public employees know that sleep disorders are associated with anemia, minimal brain dysfunction, diabetes, and metabolic syndrome. ⁴²

However, sleep disorders were deemed a vital health concern by about 90% of medical workers, and they were convinced that people experiencing such problems ought to go for treatment. Approximately 80% of the medical students demonstrate liking of sleep medicine as a profession and advocate the establishment of sleep medicine facilities. Shockingly, about 80% of the learners presumed that they or their colleagues experienced sleep disorders, and just 45% had sought medical intervention regarding the problem. ⁴²

Research on the knowledge, conviction, and experience of sleeping problems amid senior medical students in Saudi Arabia affirmed that there is insufficient understanding coupled with numerous misconceptions concerning sleep. ¹⁹

Instances of the false convictions and misapprehensions amid medical students encompass the notion that through determination, a person can triumph over sleepiness, or at least 8 hours of sleeping time are compulsory for every person. It has been affirmed that sleep-associated convictions vary between public and medical workers. Research on the knowledge, conviction, understanding, and practice towards public workers disclose a suitable level of sleep comprehension. ⁴³ Nevertheless, medical workers score poorly with respect to queries regarding beliefs. Most research studies center on specific, vital factors of sleep physiology, demands, pharmacology, sufficiency, the impact of sleeping problems, false impressions, and sleep quality.

Amid medical students across the globe, the understanding of sleep medication has been seen to be poor, with no considerable dissimilarities amid males and female learners in Saudi Arabia and other countries. ⁴⁴ There is also inadequate knowledge of sleep medicine amid medical students around the world. Moreover, medical students show a poor level of insight, discernment, and practice with regard to sleep. ^{23, 27}

A high percentage of studies on sleep disorder affirm that medical students have insufficient knowledge and misapprehension of the significance of sleep. ^{35, 43, 47} Surveys have established that approximately 40% of medical curricula do not provide edification in sleep medicine. ⁴⁵ On this note, it is evident that sleep education in present medical schools is poor and requires enhancement.

The most severe impact of inadequate education on sleep disorders is the augmented level of misdiagnosis and poor quality of treatment of sleeping problems by health professionals. ⁴⁶ Therefore, there is a dire need for a considerable syllabus reform to boost the provided sleep education. A connection has also been proved between learning by medical students (especially the excellence of their performance) and the quantity and quality of sleep. Enough sleep stabilizes and facilitates cognitive function. Cognitive ability, for instance, encoding and consolidation of memory are greatly significant for higher education students, particularly in medical schools, since such learners require the retention of a considerable level of intricate factual insight within the shortest time possible. ⁴⁷

A methodical random sample of medical learners at a university in the Kingdom of Saudi Arabia demonstrated that the students of average performance experience drowsiness even in the course of class sessions and have a higher Epworth Sleepiness Score when judged against the ones who excel outstandingly. ⁴⁸ Most of the excelling students were found to sleep early and have sufficient, quality sleep. It was then concluded that reduced nocturnal sleeping duration, going to bed late at night, and augmented drowsiness in the course of the day were strongly connected to poor academic performance among medical students. ⁴⁸

In this regard, studies establish that medical learners who get enough, quality sleep perform better in their examinations than their counterparts who have sleeping problems or inadequate sleep.

Sleep questionnaires are usually developed to assess dissimilar characteristics of sleep: quality, daytime drowsiness, the influence of disorders on normal operations, and particular sleeping problems. ⁴⁶ Questionnaires that evaluate sleep quality, for instance, Pittsburgh Sleep Quality Index, and the ones that assess drowsiness during the day, for example, the Epworth Sleepiness Scale and the Stanford Sleepiness Scale, have not been created to discover a particular sleeping problem. Other questionnaires, such as the Insomnia Impact Scale and the Quality of Life of Insomnia are set to establish the influence of sleep disorders on normal operations. ²⁴

Some other questionnaires are meant to screen just one form of sleeping disorder; the Sleep and Health Questionnaire, the Hawaii Sleep Questionnaire, and the Survey Screen for Sleep Apnea are employed in the evaluation of chronic sleep apnea.

The Insomnia Severity Index and the Spielman’s Insomnia Symptom Questionnaire are used in the appraisal of insomnia though the former type is meant for outcome instead of incidence. ¹⁴ Moreover, the Basic Nordic Sleep Questionnaire and the Berlin Questionnaire can be used in the detection of two forms of sleep disturbances whereas the Sleep Disorders Questionnaire has the capacity to evaluate even four types of disorders. Nevertheless, attributable to its length, the Sleep Disorders Questionnaire is not a practical tool in the assessment of sleeping problems amid the public. The Dutch form of Sleep Disorders Questionnaire is shorter and convenient (the only certified sleep questionnaire in Holland), but it has other restrictions that encompass unidentified dependability coefficient and accurate forecast for less than 30% of healthy respondents. ⁴⁶

Of late, the Global Sleep Assessment Questionnaire has been approved to assess and foretell numerous common sleeping problems including insomnia, chronic sleep apnea, restless legs, and sleep-related mental problems to mention a few. Nevertheless, the approval of the questionnaire entailed just a handful of healthy respondents and conclusions regarding its capacity to foretell appropriately people devoid of any sleeping problems cannot be made. Furthermore, it did not cover sleeping problems such as narcolepsy.

There was earlier no convenient sleep questionnaire that can sufficiently foretell all the sleeping problems outlined in the Diagnostic and Statistical Manual of Mental Disorders while even successfully differentiating the disorders from their complaints. This called for the creation of the SLEEP-50 questionnaire. ⁴⁶ This form of questionnaire has the advantage of being self-administered regarding the extent of an individual’s subjective sleeping problems. It also has the merit of identifying both the sleeping problems and the disorders outlined in the Diagnostic and Statistical Manual of Mental Disorders, in addition to the aspects influencing sleep.

Since SLEEP-50 has the ability to discover less widespread sleeping problems, it is suitable for the detection of sleep disorders in the target population of the same age group. ⁴⁶ Though highly incident, sleeping problems are greatly undiagnosed or ineffectively diagnosed in the adult populace and amid medical students. This could be triumphed over through the application of sleep questionnaires, especially the SLEEP-50, which act as effective screening tools for sleeping problems.

References

1. Roberts RE, Roberts CR, Duong HT. Sleepless in adolescence: prospective data on sleep deprivation, health and functioning. Journal of Adolescence. 2009; 32(5):1045-1057.
2. Luyster FS, Strollo Jr PJ, Zee PC, Walsh JK. Sleep: a health imperative. Sleep. 2012; 35(6):727-734.
3. Kripke DF, Garfinkel L, Wingard DL, Klauber MR, Marler MR. Mortality associated with sleep duration and insomnia. Archives of General Psychiatry. 2002; 59(2):131-136.
4. Ohayon MM, Reynolds CF. Epidemiological and clinical relevance of insomnia diagnosis algorithms according to the DSM-IV and the International Classification of Sleep Disorders (ICSD). Sleep Medicine. 2009; 10(9):952-960.
5. Mayer P, Heinzer R, Lavigne G. Sleep bruxism in respiratory medicine practice. Chest Journal. 2016; 149(1):262-271.
6. BaHammam A, Al-sharani K, Al-zahrani S, Al-shammari A, Al-amri N, Sharif M. The prevalence of restless legs syndrome in adult Saudis attending primary health care. General Hospital Psychiatry. 2011; 33(2):102-106.
7. Al Rajeh S, Bademosi O, Ismail H, Awada A, Dawodu A, Al-Freihi H, et al. A community survey of neurological disorders in Saudi Arabia: the Thugbah study. Neuroepidemiology. 1993; 12(3):64-78.
8. Al-Hazzaa HM, Musaiger AO, Abahussain NA, Al-Sobayel HI, Qahwaji DM. Prevalence of short sleep duration and its association with obesity among adolescents 15-to 19-year olds: a cross-sectional study from three major cities in Saudi Arabia. Annals of Thoracic Medicine. 2012; 7(3):33-36.
9. 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 Medical Education. 2012; 12(1):61-63.
10. Dregan A, Armstrong D. Age, cohort and period effects in the prevalence of sleep disturbances among older people: the impact of economic downturn. Social Science & Medicine. 2009; 69(10):1432-1438.
11. Doi Y, Minowa M, Okawa M, Uchiyama M. Prevalence of sleep disturbance and hypnotic medication use in relation to sociodemographic factors in the general Japanese adult population. Journal of Epidemiology. 2000; 10(2):79-86.
12. Dregan A, Armstrong D. Adolescence sleep disturbances as predictors of adulthood sleep disturbances—a cohort study. Journal of Adolescent Health. 2010; 46(5):482-487.
13. BaHammam AS, Al-Rajeh MS, Al-Ibrahim FS, Arafah MA, Sharif MM. Prevalence of symptoms and risk of sleep apnea in middle-aged Saudi women in primary care. Saudi Medical Journal. 2009; 30(12):1572-1576.
14. Douglass AB, Bornstein RF, Nino-Murcia G, Keenan S. The sleep disorders questionnaire: creation and multivariate structure of SDQ. Sleep: Journal of Sleep Research & Sleep Medicine. 1994; 17(2):160-167.
15. Siddiqui AF, Al-Musa H, Al-Amri H, Al-Qahtani A, Al-Shahrani M, Al-Qahtani M. Sleep patterns and predictors of poor sleep quality among medical students in King Khalid University, Saudi Arabia. The Malaysian Journal of Medical Sciences: MJMS. 2016; 23(6):94-99.
16. Sultan SA, Alhosaini AA, Sheerah SA, Alrohaily AA, Saeed HM, Al-Raddadi NM, et al. Prevalence of depression among medical students at Taibah University, Madinah, Saudi Arabia. International Journal of Academic Scientific Research. 2016; 4(1):93-102.
17. Vela-Bueno A, De Iceta M, Fernandez C. Prevalence of sleep disorders in Madrid, Spain. Gaceta Sanitaria/SESPAS. 1998; 13(6):441-448.
18. Thorpy MJ. Classification of sleep disorders. Neurotherapeutics. 2012; 9(4):687-701.
19. BaHammam AS, Alenezi AM. Narcolepsy in Saudi Arabia. Demographic and clinical perspective of an under-recognized disorder. Saudi Medical Journal. 2006; 27(9):1352-1357.
20. BaHammam AS, Alrajeh MS, Al-Jahdali HH, BinSaeed AA. Prevalence of symptoms and risk of sleep apnea in middle-aged Saudi males in primary care. Saudi Medical Journal. 2008; 29(3):423-426.
21. BaHammam AS. Sleep medicine in Saudi Arabia: current problems and future challenges. Annals of Thoracic Medicine. 2011; 6(1):3-8.
22. BaHammam AS. Knowledge and attitude of primary health care physicians towards sleep disorders. Saudi Medical Journal. 2000; 21(12):1164-1167.
23. Foley DJ, Monjan AA, Brown SL, Simonsick EM. Sleep complaints among elderly persons: an epidemiologic study of three communities. Sleep: Journal of Sleep Research & Sleep Medicine. 1995; 18(6):425-432
24. Klingman KJ, Jungquist CR, Perlis ML. Questionnaires that screen for multiple sleep disorders. Sleep Medicine Reviews. 2017; 32:37-44.
25. Harding K, Feldman M. Sleep disorders and sleep deprivation: an unmet public health problem. Journal of the American Academy of Child & Adolescent Psychiatry. 2008; 47(4):473-474.
26. Jauhar S. From all walks of life: nontraditional medical students and the future of medicine. N Engl J Med. 2008; 359(3):224-226.
27. Garcia-Jimenez MA, Salcedo-Aguilar F, Rodriguez-Almonacid FM, Redondo-Martínez MP, Monterde-Aznar ML, Marcos-Navarro AI, et al. The prevalence of sleep disorders among adolescents in Cuenca, Spain. Revista de neurologia. 2003; 39(1):18-24.
28. Janson C, Gislason T, De Backer W, Plaschke P, Björnsson E, Hetta J, et al. Prevalence of sleep disturbances among young adults in three European countries. Sleep. 1995; 18(7):589-597.
29. Gallicchio L, Kalesan B. Sleep duration and mortality: a systematic review and meta‐analysis. Journal of Sleep Research. 2009; 18(2):148-158.
30. Almohaya A, Qrmli A, Almagal N, Alamri K, Bahammam S, Al-Enizi M, et al. Sleep medicine education and knowledge among medical students in selected Saudi Medical Schools. BMC Medical Education. 2013; 13(1):133-137.
31. Alotair H, BaHammam A. Gender differences in Saudi patients with obstructive sleep apnea. Sleep and Breathing. 2008; 12(4):323-329.
32. Abdulghani HM, Alrowais NA, Bin-Saad NS, Al-Subaie NM, Haji AM, Alhaqwi AI. Sleep disorder among medical students: relationship to their academic performance. Medical Teacher. 2012; 34(1):37-41.
33. Hillman DR, Lack LC. Public health implications of sleep loss: the community burden. Med J Aust. 2013; 199(8):7-10.
34. Hammam AB, AlFaris E, Shaikh S, Saeed AB. Prevalence of sleep problems and habits in a sample of Saudi primary school children. Annals of Saudi Medicine. 2006; 26(1):7-9.
35. Gaultney JF. The prevalence of sleep disorders in college students: impact on academic performance. Journal of American College Health. 2010; 59(2):91-97.
36. Groeger JA, Zijlstra FR, Dijk DJ. Sleep quantity, sleep difficulties and their perceived consequences in a representative sample of some 2000 British adults. Journal of Sleep Research. 2004; 13(4):359-371.
37. AlFakhri L, Sarraj J, Kherallah S, Kuhail K, Obeidat A, Abu-Zaid A. Perceptions of pre-clerkship medical students and academic advisors about sleep deprivation and its relationship to academic performance: a cross-sectional perspective from Saudi Arabia. BMC Research Notes. 2015; 8(1):740-745.
38. Azad MC, Fraser K, Rumana N, Abdullah AF, Shahana N, Hanly PJ, et al. Sleep disturbances among medical students: a global perspective. J Clin Sleep Med. 2015; 11(1):69-74.
39. Sateia MJ. International classification of sleep disorders-: highlights and modifications. Chest Journal. 2014; 146(5):1387-1394.
40. Roth T, Zammit G, Kushida C, Doghramji K, Mathias SD, Wong JM, et al. A new questionnaire to detect sleep disorders. Sleep Medicine. 2002; 3(2):99-108.
41. Ohayon MM. Prevalence and comorbidity of sleep disorders in general population. La Revue du praticien. 2007; 57(14):1521-1528.
42. Leger D, Poursain B. An international survey of insomnia: under-recognition and under-treatment of a polysymptomatic condition. Current Medical Research and Opinion. 2005; 21(11):1785-1792.
43. Roberts RE, Shema SJ, Kaplan GA. Prospective data on sleep complaints and associated risk factors in an older cohort. Psychosomatic Medicine. 1999; 61(2):188-196.
44. Veldi M, Aluoja A, Vasar V. Sleep quality and more common sleep-related problems in medical students. Sleep Medicine. 2005; 6(3):269-275.
45. Wojnar M, Ilgen MA, Wojnar J, McCammon RJ, Valenstein M, Brower KJ. Sleep problems and suicidality in the National Comorbidity Survey Replication. Journal of Psychiatric Research. 2009; 43(5):526-531.
46. Spoormaker VI, Verbeek I, van den Bout J, Klip EC. Initial validation of the SLEEP-50 questionnaire. Behavioral Sleep Medicine. 2005; 3(4):227-246.
47. Wali SO, Krayem AB, Samman YS, Mirdad S, Alshimemeri AA, Almobaireek A. Sleep disorders in Saudi health care workers. Annals of Saudi Medicine. 1998; 19(5):406-409.
48. Abdulghani HM, Al-Drees AA, Khalil MS, Ahmad F, Ponnamperuma GG, Amin Z. What factors determine academic achievement in high achieving undergraduate medical students? A qualitative study. Medical Teacher. 2014; 36(1):43-48.