Our cross-sectional study of Egyptian public officials showed a higher prevalence of sleep disorders among women than men. Moreover, the factors correlated with the total sleep disorders, and each specific disorder varied by gender. The family's income and the number of minors were associated with the overall and specific sleep disorders in women, while residence, working an extra job, shift work, and perceived social support from the family correlated with the men’s total and specific sleep disorders. Age, job demands and control, and histories of chronic diseases and depression correlated with sleep disorders in both genders. Higher education was associated positively in women and inversely in men with the odds of having sleep disorders.
The estimated prevalence in our study is in line with those estimated in American and Asian working populations. An American study reported that the prevalence of sleep disorders was 19.2% among 6338 workers aged ≥ 18 who participated in the National Health and Nutrition Examination Survey (Yong et al. 2017). Among 464 Asian workers (64% Chinese) aged 21 years or more, the prevalence of poor sleep quality was 43.2% (Thach et al. 2020). The prevalence of poor sleep quality was 15.5% among 470 Iranian workers (Yazdi et al. 2014). However, a lower prevalence of 3.3% was indicated among 7112 paid workers who participated in the 2nd Korean Working Conditions Survey (Heo et al. 2013).
There was a higher prevalence of sleep disorders in females than male Egyptian public officials. Similarly, among 1171 daytime Korean workers, the prevalence of sleep disorders was 38.1% in women and 25.8% in men (Kim et al. 2018). In a large French longitudinal study of 21,378 workers, the prevalence of sleep disorders among women increased from 25.7% in 1990 to 29.4% in 1995, and that of men increased from 19.1% to 21.0% (Ribet and Derriennic 1999). The postulated mechanisms for the higher prevalence in women and the different correlates among both genders include the earlier and shorter females’ circadian clock than males (Duffy et al. 2011) and the higher domestic burden on working women (Eshak 2019).
There is growing evidence that the risk of sleep disorders increases with age (Evans et al. 2021). However, age in our study was inversely associated with the odds of having sleep disorders in both genders, matching the findings among the Korean working population (Kim et al. 2018). The younger employees might consider sleep limiting their activities; thus, maintaining a regular sleep schedule was not a priority (Kim et al. 2018). Ribet and Derriennic indicated in their large longitudinal French study that the growing prevalence of sleep disorders with age was more attributed to a reduced rate of sleep disorders disappearance than to additional incidences with age (Ribet and Derriennic 1999).
In our study, sleep disorders increased among highly educated women and decreased among highly educated men, which adds to the discrepant association between education level and sleep disorders. Sleep disorders were attributed to lower educational attainment in some studies (Thach et al. 2020) and higher educational attainment in other studies (Yong et al. 2017). Heo et al. (2013) indicated both university or above-, and junior high school-educated Koreans had significantly more sleep disorders than high school graduates. With the possible gender discrimination at the worksite (Jayachandran 2014), highly educated female public officials may have significantly less job satisfaction than males. On the other hand, highly educated females who succeed in attaining a relatively higher employment status may have greater obligations to work, leading to long working hours and inadequate and poor sleep (Heo et al. 2013). This postulation was supported by the finding that women with a high income had significantly higher odds of having sleep disorders.
The association between BMI and sleep disorders is in tone with the previous literature. The elevated levels of cortisol, responsible for the desire to consume energy-dense foods in patients with obesity, were found to play a role in increasing the risk of nocturnal awakening and insomnia (Chan et al. 2018).
The associations between work environment (high job demands, low job control, working an extra job, and shift work) and sleep disorders found among the Egyptian public officials agree with those in other nationalities (Ribet and Derriennic 1999; Kim et al. 2018; Thach et al. 2020). Shift work can disrupt the circadian rhythm. In addition, stressful work environments could induce psychosocial stress, hormonal disturbance of melatonin, cortisol, and other hormones and may initiate/aggravate mental health problems, leading to poor sleep quality (Fernandez-Mendoza and Vgontzas 2013; Heo et al. 2013; Yazdi et al. 2014; Yong et al. 2017).
We found significant associations between physical and mental health statuses and sleep disorders. A consistent high prevalence of sleep disorders was reported in chronically ill patients (Ibrahim and Wegdan 2011; Abd Elsadek et al. 2019; Mansour et al. 2020); however, many longitudinal reports indicated sleep disorders as a risk factor for physical and mental health problems, suggesting bidirectional associations of sleep disorders and health status (Alvaro et al. 2013).
One of the current study’s strengths is the subtype analyses of sleep disorders which gave a clear understanding of the correlates. For example, the number of minors in the family emerged to associate with the women’s interrupted sleep and waking up too early, which is plausible considering the caregiving role of women in the family. Another example was that job demands were associated with all subtypes of sleep disorders in females. On the other hand, in men, job demands and shift work was associated with difficulties falling asleep, job control was associated with interrupted sleep, and working an extra job was associated with waking up too early and waking up tired. Some researchers pointed out that work overload and shift work could be the most significant occupational precipitating factors of insomnia (Heo et al. 2013; Pilcher & Morris 2020).
Study limitations that should be mentioned include the inability to infer causality for the observed associations between the studied factors and sleep disorders because this was a cross-sectional study. Second, the recruited participants were public officials; thus, we cannot guarantee the generalizability of the study findings to employees in the free enterprise. Third, we studied common self-reported sleep disorders of the JSEQ, which showed a high validity in Egyptians (Eshak 2019); however, JSEQ does not cover other sleep disorders such as sleep apnea syndrome, restless leg syndrome, and hypnotic medication use. Indeed, the prevalence of sleep disorders could vary by using different diagnostic tools to estimate sleep disorders. Longitudinal studies using polysomnography are recommended to confirm the observed associations.