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The Relationship between Sleep Quality and Quality of Life of Retired Elders

Article history Received 27 Nov 2018 Accepted 27 Nov 2019 Introduction: Survey about the issues and problems related to elderly in order to improve their Quality Of Life (QOL) of this increasing population has become a universal concern. Even though aging is a natural process but many effective factors such as rest and sleep pattern can affect this process. So this study aimed to determine the relationship between sleep quality and QOL of the retried elderly members of Isfahan retirement center


Introduction
The composition of the world's population is changing, and developments in medical knowledge and amazing technologies in the today's world have accelerated this process, and consequently increased life expectancy as one of the consequences of this rapid development has increased the number of elderly people. According to the 2016 census, 9.27% of the population of Iran are 60 years old and older (1).
The poor sleep quality is one of the most common problems faced by the elderly people. Studies have shown that one of the factors affecting the sleep quality in the elderly people is the change in the mood and structure of sleep and rhythm of circadian, so that these changes can lead to sleep disorders and repeated complaints (2,3). It is necessary to explain that the main cause of sleep problems in elderly people is not biological changes in the circadian rhythm, but it is diseases, the effect of drugs, depression and anxiety and restricted movement (4). Research has shown that sleep with poor quality, after headache and gastrointestinal disorders ranks third in terms of elderly problems and it is one of the common complaints and the reason for referring to physicians (5). Epidemiological studies in Sharifi et al.
On the other hand, sleep problems in the elderly people can also affect the "self-perception" in elderly people, and self-perception can also determine how a person behaves and has a useful function that can somehow affect the Quality Of Life (QOL) of the elderly person (7).
The concept of QOL is considered as an essential indicator of health and since it involves many aspects such as physiological, functional and existential aspects, paying attention to it has particular importance (8). One of the factors affecting the QOL is sleep quality. A study in North Taiwan showed that insomnia and mental symptoms causing from it are related to their poor QOL (9). In addition, a study conducted by Kord et al. showed that elderly people will enjoy better sleep quality by changing their lifestyle (10). The results of other study also indicated that elderly people with mild to severe drowsiness were suspected of mental health problems (11).
Although the main challenge of health in the 20th century was to increase life expectancy, the main challenge of health is better QOL in the 21st century (12). However, investigations in Iran show that 62% of elderly people are accidental, 22% are social and 16% are welfare and health. This negligible share shows that the QOL of the elderly people has not been considered so much (8). Considering increase in elderly people population, significant improve their QOL, insufficient information about it; importance of sleep quality among aging people and limitation of studies in this area in Iran, the present study is conducted to determine the relationship between sleep quality and QOL of the retried elderly members of Isfahan retirement center.

Research design and participants
The present study was a cross-sectional research that was done on 192 retired older adults over 60 years of age who were referred to Isfahan Retirement Center by simple random sampling.
Inclusion criteria were having age 60 years and higher and the ability to answer the questionnaire. Exclusion criteria were recognized mental and physical and psychological disabilities (self-report).

Instrumentation
The sampling tool in this study, except for the individual information form (age, gender, level of education, marital status), included two questionnaires including Pittsburgh Sleep Quality Index (PSQI) and Elderly Quality of Life Questionnaire (LIPAD).
PSQI has 9 questions in 7 dimensions assessing the sleep quality, sleep delay, useful sleep duration, sleep adequacy (proportion of useful sleep duration from the time spent in bed), sleep disorders (night waking), rate of using sleeping drug, and impaired daily function (problems associated with insomnia during the day). The score for each question is in the Likert form and between 0 and 3, and the score 3 on each scale indicates the maximum negative. The total score of this questionnaire is 0 to 21, and according to previous studies, the overall score of 6 and above indicate poor sleep quality (13). Buysse et al. in their study reported the sensitivity and characteristics of questionnaire 0.86.5 and 0.86.5%, they reported internal validity of the questionnaire 0.83, and using re-test, they reported its reliability 0.85 (13). In addition the reliability and validity of the questionnaire were confirmed by Ahmadi et al. in Iran (14).
The elderly quality of life questionnaire (LIPAD) that developed under the support of World Health Organization and studied by De Leo and Makaran in the cities of Padua and Brescia in Italy, Leiden in the Netherlands, and Helsinki in Finland (15). It is used relatively fast and understood by the elderly people with a low level of education easily. The questionnaire examines elderly QOL in 7 dimensions of physical activity (5 questions), depression and anxiety (4 questions), self-care (6 questions), mental performance (5 questions), social function (3 questions), sexual function (2 questions) and life satisfaction (6 questions). Each question has four options scored from zero (the worst state) to three (the best state) and in has total 31 questions, with a minimum score of 0 and a maximum score of 93. Validity and reliability of this questionnaire have been evaluated appropriate in the study conducted by Hesamzadeh et al. so that its validity has been approved by 10 different university professors and its Cronbach alpha was calculated 0.83 to assess its reliability (16). Additionally, its reliability in the research conducted by Sajadi and Biglarian was confirmed by Cronbach's alpha of 0.87 (17).

Data collection
After obtaining permission from the Faculty of Nursing and Midwifery of Isfahan University of Medical Sciences and presenting it to the Isfahan Retirement Center and obtaining permission from this association officer, sampling was carried out. In this study, a random sampling method was used. Among files of referrals to the association, file number of all persons aged 60 and higher was extracted and then random numbers table was used to determine the sample members. Then, among those who met the inclusion criteria, 190 samples were selected. Questionnaires were completed in self-reporting form in one stage. The sampling lasted about two months.

Ethical considerations
The Research Ethics Committee of Isfahan University of Medical Sciences approved this study (ethical code IR.MUI.REC.1394.2.006). Moreover first, the participants were given enough explanation about the study objectives and then their written consent for participating in the research was obtained.

Data analysis
The data of this research were quantitative and descriptive statistical methods were used for the analysis. In addition, SPSS 21 software was used to analyze the data. Pearson correlation coefficient was calculated to determine the relationship between quantitative variables of sleep quality and QOL. T-test was used for two-domain variables and ANOVA for multi-domain variables.

Results
Out of 190 participants in the study, 177 completed the questionnaires. The age of the samples ranged from 60 to 82 and the majority (82%) were in the age group of 60-69 years. Among the participants 54.2% were men, 59.3% in higher education, 10.2 % under high school and 30.5 % high school education. The Marital status of participant was 2.8% single, 85.3% married, 9.6% spouse deceased and 2.3% divorced.
The results show that the mean score of sleep quality in the elderly people was 6.63 ± 3.41 (range 0-21), suggesting a mild prevalent disorder in the sleep quality of elderly people. In addition, the mean score of elderly people QOL was 61.15 ± 9.97 (range 0-93). The highest and lowest score was related to self-care dimension (12.78 ± 2.92) and social dimension (6.14 ± 1.4), respectively. Pearson correlation coefficient also showed that there is a significant relationship between sleep quality score and QOL score and its dimensions (p < 0.05) ( Table 1).
In addition Pearson correlation coefficient shows that age has significant correlation with variables of sleep quality (r = 0.356, p < 0.001) and QOL (r = -0.471, p < 0.001). Spearman correlation coefficient also shows that the level of education has a significant relationship with sleep quality (ρ = -0.32, p < 0.001) and QOL (ρ = 0.285, p < 0.001).
Independent t-test also shows that the mean score of sleep disorder in females is significantly higher than that in males (p = 0.004), but the mean score of QOL is not significantly different between males and females (p = 0.29) ( Table 2). ANOVA test shows a significant relationship between sleep quality score of elderly people and their marital status (p = 0.01). As seen in the table, the mean sleep quality is in the best state in married people (6.3 ± 3.33) and it is in the worst state (6.5 ± 4.7) in single people. In addition, there is a significant relationship between the QOL score and the marital status of the elderly people (p = 0.038), and the mean score of QOL in married people is in the highest level (62 ± 9.7) and it is in the lowest level (52.1 ± 14.4) in the single people (Table 3).

Discussion
In this study, the relationship between sleep quality and QOL of elderly people who were member of Isfahan Retirement Center was studied. The results of this study showed that subjects of this study have mild sleep disorder. This finding is in line with the results of epidemiological studies, indicating a high level of sleep disorder in societies and an increase in its prevalence with age (18,19). The results also showed that the QOL of elderly retired people is moderate, which is consistent with the results of previous studies (20,21). Habibi et al. in their study indicated the mean score of QOL in elderly people of west of Tehran was moderate (22).
There were significant and positive correlations between sleep quality and QOL and its dimensions in the retried elderly. In other words, people who have better sleep quality have also good QOL, and better sleep quality is correlated with physical, self-care, cognitive state, better social functioning, and higher satisfaction and lower depression. Confirming the results of the study conducted in Taiwan, results indicated that poor sleep quality, insomnia and psychological symptoms caused are associated with poor life quality (9). Additionally, other studies showed that there was a strong negative correlation between poor sleep quality and QOL in the elderly people (11,23,24). These results confirmed that sleep health is important for improving QOL of elderly people, and those who had poorer sleep quality had a worse QOL. According to the results of other studies, chronic insomnia is associated with results such as daytime drowsiness, fatigue, low energy, depressed mood, psychomotor impairment, vulnerability, cognitive impairment, and reduced concentration and attention, affecting the QOL of the elderly people (25,26).  The results also showed with aging, the sleep quality of the elderly people and their QOL decrease. Other studies show that increasing age also leads to a decline in QOL in most dimensions (27,28). This result may due to the greater frequency of chronic medical conditions in advanced age In addition, the results of this study showed that females had more sleep disorders than males. This might be due to the fact that menopause plays an important role in the structural changes in the sleep of elderly women, and in the post-menopause period, they sleep quality declines. These findings are consistent with the results of other studies, in better sleep quality was reported in males (6,19). The results also indicate that married people couples have good sleep quality. In fact, those who are married have a great source of social support that is family. Conversely, widows and single people are deprived of this support. Previous studies have shown that being single, divorced or widowed are factors that have a positive relationship with insomnia and sleep disorders (29)(30)(31).

Conclusion
The findings of this study suggest that poor sleep quality in retired elderly people is associated with lack of QOL. Therefore, paying attention to this issue is important in health supporting programs. Accordingly, it is suggested that programs and approaches to be considered to improve the sleep quality of the elderly people so that they have a better QOL. Regarding the relationship between QOL and sleep quality in the elderly, it is recommended further studies should be done to indicate this relationship and the transposition of each of these factors compared to each other.

Study limitations
A limitation of this study is conducting an investigation in one city with specific lifestyles and culture and in a specific group of elderly people (retired). Small sample size that led to wide range of SD must be taken into consideration in examining the results. Therefore, it is recommended that studies to be conducted in different cities, in different groups of elderly people and in larger size.