Current status of sleep quality in Taiwan: a nationwide walk-in survey

Sleep disorders are problems of the sleeping patterns, and broadly classified into four main types, including problems of falling and staying asleep, staying awake, sticking to a regular sleep schedule, and unusual behaviors during sleep [1]. An estimated 25–30 % of the general adult population and a comparable percentage of children and adolescents chronically suffer from sleep disorders that are proven contributors to disability, morbidity, and mortality [2]. Sleep disorder can occur as a primary disorder or, more commonly, it can be co-morbid with other physical or mental disorders [3]. When a person suffers from difficulty falling asleep and/or staying asleep with no obvious cause, it is referred to as insomnia [4]. Around 50 % of patients with depression have co-morbid insomnia, and depression and sleep disturbance are, respectively, the first and third most common psychological reasons for patient encounters in general practice [5]. Insomnia doubles the risk of future development of depression [6] and increases the risk of a range of health concerns and chronic diseases, including substance abuse, poor daytime functioning [7], dissatisfaction with one’s quality of life [8], obesity [9], diabetes mellitus [10], and hypertension [6, 11]. These associations contributed to a significant economic burden, and annual sleep disorder-related direct and indirect cost estimates exceed $100 billion in the United States [12] and $40 million in Taiwan [13]. Understanding the situation of sleep is an essential first step in establishing public health priorities for preventing sleep-related health concerns.

Although information regarding the national sleep disorder prevalence rate is lacking in Taiwan, two cross-sectional surveys of insomnia, the most common sleep disorder, in Asian countries were conducted in 2003 [14] and 2005 [15]. The cross-sectional survey with a face-to-face interview in 2003 defined insomnia as having at least one of three types of insomnia symptoms (i.e., difficulty initiating sleep, difficulty maintaining sleep, and early-morning awakening), The study revealed that the age-adjusted prevalence of insomnia was 10.3 % in Taiwan, which was higher than that in Japan (4 %) and Korea (9.9 %) [14]. Another nationwide data of 36,743 men and women aged 18 years and above from the 2005 Survey of Social Development Trends-Health Security in Taiwan were analyzed. This 2005 survey used the insomnia self-assessment inventory which is a 13-item self-reported inventory designed by the WHO worldwide project on sleep and health to measure insomnia and found that over 25 % of Taiwanese adults’ experienced insomnia [15]. Although these two studies were both nationwide survey, they were published several years ago [14, 15]. Other prior studies were limited to a specific age group (i.e., children [16], adolescents [17] or elderly [18]), gender [19], or medical condition [20].

A recent eight-year nationally representative study used the National Health Insurance database to assess the longitudinal healthcare-seeking prevalence and incidence of insomnia with ICD-9 of 780.52, 307.41, and 307.42 [21]. The result revealed that the prevalence of insomnia was 5.4 % for women and 3.0 % for men in 2009; the incidence of insomnia was 1.6 % for women and 1.3 % for men. Although this was a recent nationwide population-based cohort study, it reflected the prevalence and incidence of health-seeking behavior and diagnosis of insomnia and was not the prevalence of symptoms or a sleep complaint. Screening, in medicine, is an important strategy used in a population to identify an unrecognized disease in individuals without signs or symptoms. Therefore, we conducted this screening survey to determine the current status of sleep quality in the general population in Taiwan.

This study provides updated information on the current status of sleep quality in the general Taiwanese population and compares the difference among the four areas in Taiwan. In this study, we found that females were more incline to participate this walk-in screening, that may be also resulted from there is female predominant for people aged greater than 50 years old in Taiwan [28].

We also observed that the mean age of all recruited participants was significantly older in the eastern area than in the other areas of Taiwan. This may be related to the finding in the recent “Report on the Survey of Citizens’ Life Status in the Taiwan Area” published by the government, that the eastern area has a higher proportion of older persons than other areas. The government study reported that 11.5 % of the population in Taiwan is aged (>65 years old), with 10.8 % in the north, 11.8 % in the central area, 12.4 % in the south, and 13.4 % in the east, as of 31 December, 2013 [29]. Besides, the sleep duration was longer and the proportion of hypnotics used was greater in eastern Taiwan. Despite our new finding of a higher proportion of hypnotics use in eastern Taiwan, no updated related studies have addressed this issue. Further studies using randomized sampling are necessary to clarify these issues.

With regard to the prevalence of hypnotics use, 11.6 % of all participants, ranging from 5.6 % in the northern area to 25.0 % in the eastern area, used hypnotics. As for other countries, the prevalence of benzodiazepine use was 31.4 % in Chile [30], that of hypnotics use in Spain was 12.3 % [31], and in the USA, 6.2 % [32]. The wide variation in prevalence rates of hypnotics use reported in different countries can largely be explained by differences in definitions of hypnotics use, the healthcare system, the availability of hypnotics, and even the observation period.

This study found that 46.6 % (n = 354, total = 760) of the participants had a PSQI score greater than five, which was indicative of poor sleep quality. The prevalence of poor sleep quality among Taiwanese showed a progressive increase in this study compared to previous studies, which were conducted in the different period with the different definition of sleep disorder [14, 15]. In contrast to other studies [21, 33], which suggested that several demographic factors (e.g., female sex and increasing age) were associated with sleep problems, there were no similar results in this study. We also found that 21.8 % of the participants with poor sleep quality had used hypnotics to help fall asleep in the past 4 weeks. Hsu et al. conducted an eight-year nationally representative study and found that the prevalence of clinic-visiting behavior for sleep disorder was 5.4 % for women and 3.0 % for men in 2009 [21]. This inconsistency may be due to the fact that our data were based on the actual population prevalence rather than healthcare-seeking behavior, although healthcare-seeking behavior may be an indicator as this could represent a significant problem. However, Hsu et al. used the National Health Insurance database to assess the healthcare-seeking prevalence, which only included the western medicine. Moreover, the participants were not asked about the types of sedatives/hypnotics used in our study, and all agents were included in one category. Further detailed information on the definition of hypnotics is needed for clarity because Chinese herbal medicine or health (functional) foods are popular in Taiwan.

The PSQI scores and the proportion of individuals with poor sleep quality were significantly higher in the northern area than in other areas. A cross-sectional survey was conducted among community-dwelling elderly in northern Taiwan between March 2009 and November 2009 and found that as much as 41 % of individuals had sleep disorder [34] although the study population was limited to the elderly. A study cited above also found that the prevalence of sleep disorder was higher among individuals who were living in cities with the highest urbanization level [21]. The average age of poor-sleep-quality individuals was still older in the eastern area due to the more aged population, and they were still predominantly female. Of interest, the proportion of hypnotics use among poor-sleep-quality individuals was significantly lower in the northern area, although those individuals had the shortest sleep duration. In contrast, the proportion of poor sleep quality was lowest in the eastern area, but the individuals with poor sleep quality in this area had the longest sleep duration. That may be related to the highest proportion of hypnotics use and the differences in urbanization and culture. However, there were relatively few participants from the eastern area in this study. We still need further studies with larger, randomized samples to confirm this result.

In the analysis of PSQI subscale scores there were significant differences among the four areas in Taiwan, except ‘subjective sleep quality’ and ‘habitual sleep efficiency’. The poor-sleep-quality individuals in the eastern area had more problems with ‘sleep latency’ and ‘use of sleeping medication’; those in the northern area had more problems with ‘sleep duration’ and ‘daytime dysfunction’. The ‘daytime dysfunction’ score was highest in the northern area, which may be related to this area having the shortest sleep duration. It may be that different local conditions and customs in different areas lead to different sleep problems.

It is important to know the status of sleep quality because there are many co-morbid conditions that can present with sleep problems, such as depression and anxiety, as well as chronic medical conditions. Co-morbid conditions have a bidirectional relationship with sleep disorder, with each influencing or exacerbating the other and requiring concurrent assessment and management. Although the study design was not a randomized sampling method to examine the prevalence and incidence of sleep disorder in Taiwan, it provided the population-based and updated information of sleep quality coming from four parts, northern, central, southern, and eastern part of Taiwan, to have its overall examination for sleep quality and reported the frequency of hypotonic drugs used. Besides, the same PSQI [27, 35], a validated sleep screening questionnaire in primary care, was used to screen the sleep quality in Taiwan. In future, we may consider adding this validated sleep screening questionnaire to the routine health examination (i.e.: civil servant, workers, the elderly…etc.) to understand the sleep situation of different populations and even apply it to other countries to have the homogeneous results to compare.

There are several limitations in this study. First, the participants were not recruited using randomized sampling from the general population, such that the results may not be representative of the entire Taiwanese population. Second, we had no detailed information about co-morbidities and education and no information on any further diagnosis to clarify the subtype of sleep disorder. However, the PSQI has been validated with reliable sensitivity and specificity in screening sleep quality, and this study was focused on screening, not diagnosing. Third, the prevalence of poor sleep quality may be under-estimated because only physically independent people could join the “walk-in” screening program. Finally, the design of this study was cross-sectional, which consequently ruled out a reliable separation of primary sleep complaint from sleep complaint secondary to another disorder or condition. Thus, a large-scale longitudinal study is needed to identify the relationship between sleep problems and its many co-morbidities and correlates, ex.: depressed disorder.

This study found a high ratio of poor sleep quality among Taiwanese, especially in the northern area, and about one-fifth of poor-sleep-quality individuals had used hypnotics in the past 4 weeks to help fall asleep, with the highest ratio in the eastern area. Sleeping quality is a crucial issue in Taiwan.