Introduction
Shiftwork refers to a broad range of non-standard work schedules, ranging from occasional on-call overnight duty to rotating timetables, to stable, permanent night work, and programs demanding an early awakening from nocturnal sleep [
1]. It includes fixed early morning, evening, and night work, as well as roster and rotating three-shift work [
2]. Evidence showed that there are various shift schedules. The medical nurses usually provide a 24-hours service, on rotating schedules while the eight‐hour and 12‐hour shifts are the most common scheduling systems [
3]. The National Sleep Foundation defined shift-work sleep disorder (SWSD) as a chronic condition that is directly related to a person’s work schedule. SWSD is considered a ‘circadian rhythm sleep disorder’ (CSRD) by the International Classification of Sleep Disorders 3rd edition (ICSD-3) [
4,
5]. Circadian rhythm sleep disorder is a sleep pattern disorder caused by changes in biological hours in humans [
6]. Shiftwork sleep disorder is characterized by insomnia or sleepiness that occurs in association with Shiftwork [
7].
Studies done in developed and developing countries showed that a significant number of nurses suffer from shiftwork sleep disorders [
8,
9] Results of various studies indicated that a huge number of nurses engaged in Shiftwork were found to be affected by shiftwork-related sleep disorders. According to an e-mail-based cross-sectional study done in Newcastle upon Tyne, North East England, the prevalence of poor sleep quality (PSQI > 5) in shift-working nurses was 78% [
10]. In a cross-sectional study done in seven central Italian hospitals, 52.1% had suffered from poor sleep quality [
11], another study done among nurses working in nocturnal and diurnal shifts in a public hospital, the prevalence of bad sleep reported was 68.3% [
12]. Similarly, in a study done in Sweden, night shift insomnia was 67% in three-shift rotation work and 41.7% in nurses with permanent night work [
13].
In Asian countries, cross-sectional studies conducted among nurses revealed that the prevalence of SWSD was 24.4% in Japan [
14], 32.2% in South Korea [
15], 75.0% had a significant sleep problem, and 39.7% of subjects had inadequate sleep stability in Northern Taiwan [
16], and 24.6% of the nurses had experienced at least one of the five insomnia symptoms in Thailand [
17].
The findings of a cross-sectional study conducted on nurses working in hospitals in the south of Iran showed that 56
% of them had signs of insomnia, and of all the participants, 78.5% were sleepy, 16.5% were very sleepy, and 5% were severely sleepy [
18]. Studies in some African countries reported that SWSD affected 43.2% and 20.8% of nurses in Nigeria and Ghana respectively [
19,
20]. A comparative cross-sectional study conducted in Egypt, 73% of nurses working in a shift had poor subjective sleep quality [
21].
Similarly, a study in Ethiopia found that about a quarter (25.6%) of the nurses experienced SWSD [
22]. Different studies reported factors like age, sex, Shiftwork -related factors [
23‐
25], substances use (caffeine, alcohol, cigarettes and others) [
26‐
28] and using different forms of sleep aid [
24] were associated with SWSD among nurses. One study conducted among health professionals revealed that khat chewing was significantly associated with SWSD [
29].
The shift-work sleep disorder can be associated with decreased attention and deficit in cognitive functioning which in turn decreased performance that may contribute to a higher propensity for mistakes/near misses/accidents. It is also associated with an increased prevalence of medical disorders such as cancer, decreased quality of life, and increased risk of mood disorders (anxiety and depression) [
30‐
33]. Studies indicated that poor sleep quality and insufficient sleep contribute to psycho-physiological health problems such as fatigue, emotional disturbance, and cardiovascular disorders [
34,
35]. It also affects decision-making ability and an increased propensity for accidents both on and off the job and results in decreased efficiency and productivity. Moreover, it increases the risk of making medical errors, compromised healthcare quality, patient safety and occupational injuries [
36,
37]. SWSD significantly increased workers’ absenteeism which harms employers economically [
30]. Regarding the management of SWSD, designed bright‐light exposure, taking naps [
38,
39], shift schedule rearrangement [
38] and taking drugs like Armodafinil are used to treat and prevent SWSD [
40].
Nurses use or abuse different types of substances, like non-prescribed medications, alcohol, khat or cigarette to alleviate the stress associated with shift work [
22,
41]. Shiftwork by itself was associated with nurses’ use/abuse of substances [
42].
In Ethiopia, there are no policies designed to prevent shiftwork-related sleep disorders. There is a paucity of information regarding the extent of SWSD among nurses, particularly in Eastern Ethiopia. This study tried to explore the association of SWSD with depression, anxiety, and stress that were not addressed in the previous studies done in the country. Therefore, the findings from this study could generate local evidence that would inform policymakers & local planners to design cost-effective strategies that reduce adverse health outcomes of SWSD among nurses in Ethiopia.
Discussion
In the current study, the magnitude of SWSD was 30.4% (95%; CI: 25.4–34.5). Being female, working more than 11-night shifts on average per month in the last 12 months and nurses who consumed khat in the last 12 months were significantly associated with SWSD.
According to this study, nearly one in every three nurses suffered from a shiftwork sleep disorder that adversely affects the health of nurses, and patient’s safety, satisfaction, and rendered care quality. Empirical evidence indicated that circadian rhythm sleep disorders, insomnia, and excessive sleepiness are widespread in night-shift workers that are associated with substantial morbidity including accidents and absenteeism [
30]. The result of this study was in line with a study conducted in Addis Ababa, Ethiopia [
22]. However, it was found higher than in studies carried out in Japan [
14] and Ghana [
50]. The possible justifications for the observed discrepancy between the current study to the study done in Japan [
14] might be due to the tool difference. A study in Japan used only the three questions of ICSD-3 criteria for assessment of SWSD and included all nurses working in two university hospitals in the Tokyo metropolitan while this study was a multicenter and the study participants were recruited randomly.
In the Ghanaian study [
50], shiftwork sleep disorder was assessed with a tool which assessed the average amount of hours each nurse has for sleeping, but in our study SWSD was determined by ICSD-3, Insomnia and Excessive daytime sleepiness combined together, in addition to this sample size used were also lower than the sample size of the current study which might have caused the noted discrepancy. In addition to the above possible reasons, also the effect of khat might be the other reason which caused the discrepancy, as it is known that khat is the most commonly consumed substance in eastern parts of Ethiopia, which was significantly associated with sleep problems [
51,
52]. On the other hand, compared to studies in Nigeria ( 43.2%) [
23], Egypt [
21], and England [
10], the finding of the current study was lower. The possible justification for the discrepancy was the difference in study design and sample size. A the study done in Nigeria [
23] used a case control study design with a smaller sample size and the current study employed a cross-sectional study design with a relatively larger sample of nurses. There was also variation in tools used for assessing SWSD. Studies were done in England and Egypt used Pittsburgh Sleep Quality Index (PSQI) while the current study determined SWSD by ICSD-3 criteria, BIS and ESS.
Being female appeared to be associated significantly with SWSD, which was in line with the systematic review conducted in 2011[
25] and a community cohort study in Toronto, Canada, [
53]. The possible reason for this association might be that there is a biological difference between males and females that females have common changes in hormonal levels; that may impact the sleep. Gonadal hormone cycles affect the sleep patterns of women during the menstrual cycle and menopause. This can result in more insomnia and frequent waking up during the sleep cycle [
54].
In the current study, working more than 11-night shifts per month on average in the last 12 months showed an association with SWSD; this finding was consistent with the study done in Addis Ababa, Ethiopia [
22] and South Korea[
55] which assessed shiftwork tolerance among rotating shiftwork nurses. One possible explanation is that having less off-time leads to less sleep duration, which may result in shiftwork type circadian sleep disorder. While, night work does not necessarily limit nurses’ time to rest, a frequent night shift limits nurses’ opportunity for sleep and may cause them to spend a lot of time on non-work activities in between Nights.
Consuming khat in the last 12 months was positively associated with SWSD; this association might happen due to Cathinone (alkaloids found in khat leave which have stimulant activity similar to amphetamines). Using khat reduces dopamine re-uptake and activates dopaminergic pathways involved in the regulation of sleep. After the khat session, the user usually experiences a depressed mood, irritability, anorexia, and difficulty sleeping [
56] and this might lead to circadian rhythm type sleep disorder or SWSD.
Strengths and limitations of the study
This study included nurses in different types of hospitals like teaching hospitals, specialized hospitals, and general hospitals, and it was a multicenter study which generates vital evidence. The study used the standard and validated tools which facilitated approximating the burden of SWSD.
Though several efforts were made, this study had its limitations. Those nurses diagnosed with SWSD could also be diagnosed with some other forms of sleep disorders. Yet, some other nurses might have been transferred to daily shiftwork schedules Asking nurses who were expected to have knowledge about the adverse effects of substance use might introduce the risk of social desirability bias. There was also the risk of recall bias, and no measure was taken to minimize it. The nature of a cross-sectional study design was another major limitation since it cannot show temporal relationships between the dependent and the independent variables.
Conclusion
About one-third of the nurses working at public hospitals in Harari Reginal State and Dire Dawa Administration, Eastern Ethiopia had SWSD. Being female, working an average number of nights > 11 per month in the last 12 months, and khat use showed a positive statistically significant association with the shiftwork sleep disorder. The prevention of shiftwork sleep disorder should focus on early detection, having a policy on khat use, and taking rest/recovery into account when scheduling work time. Moreover, longitudinal, and controlled trial studies will be necessary to highlight the effect of SWSD on the well-being of the nurses, patients’ safety, and the health care system.
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