Factors Related to Depression and Mental Health That Affect the Quality of Life of the Elderly

The purpose of this study was to provide basic data for the healthcare of the elderly by identifying the effects of depression and quality of sleep on the lives of the elderly. The subjects of this study were 120 elderly people who used the elderly welfare center and senior citizen center in one of the cities in South Korea, who understood the purpose of the study and signed the consent form for participation in the study. This study is a descriptive correlation study using a questionnaire to compare and analyze the effects of depression and quality of sleep on the quality of life of the elderly. Data were analyzed using the SPSS 25.0 program. According to general characteristics, the level of depression, quality of sleep, and quality of life were analyzed by frequency, percentage, mean, and standard deviation. The level of depression, quality of sleep, and quality of life, as measured by the general characteristics, were evaluated by the t-test and ANOVA. The quality of life, depression, and quality of sleep were analyzed by Pearson's correlation analysis. Linear regression analysis was performed to analyze the factors influencing sleep quality. As a result of this research, depression, psychological, and social domains had positive correlations, and depression and biological domains had negative correlations. As a result of this research, quality of sleep was found to have a negative correlation with the psychological domain and quality of sleep was found to have a positive correlation with the biological environment domain. Based on this research, this author proposes that research should be attempted later with the elderly who were classified as the elderly who are living alone, the elderly who are living at home, and the elderly at the facilities as the subjects. Therefore, depression and the quality of sleep have a big influence on the health condition of the elderly because they may be the important health problems that cannot be overlooked in terms of the quality of life. Furthermore, there is a need to develop a continuous, specific, and practical healthcare program that can manage depression and quality of sleep in old age.


Introduction
With the industrialization of modern society in the 21st century due to the development of medicine and science, the quality of life has been increasing. In addition, with the improvement in the quality of medical treatment, the elderly population has also been increasing rapidly. Among the total population as of 2019, the elderly who are 65 years old and older accounted for 14.9%, which means that they have already entered the elderly society. Moreover, it is anticipated that, until the year 2067, it will increase by 46.5% [1].
Although depression can appear throughout the whole process of the developmental phases of human beings, it has received attention because it is a psychological and social characteristic of the elderly [2].
Regarding the depression of the elderly, the lowering of the ability to adapt to the many changes appears by generally experiencing the internal and external changes caused by aging from a psychological aspect. At this time, the psychological change that stands out is the anxiety or feeling of depression due to stress. Ten, this acts as a cause that lowers not only the level of satisfaction regarding life but also the quality of life [3]. To the elderly, depression is a cause that lowers self-esteem and quality of life [4][5][6]. In addition, it also has a negative infuence on the quality of life of the elderly in the social and national dimensions by causing problems such as functional disorders in everyday life activities, sleep disorders, and suicide acts due to important health problems, so health management of the elderly is needed [7,8].
Te elderly cannot have deep sleep at night as the amplitude of the circadian rhythm is decreased by a change in the biorhythm. Terefore, they wake up frequently or show the phenomenon of daytime sleepiness. In addition, with the changes in sleep patterns, their sleep latency continues and their sleep efciency decreases. According to a recent investigation into the health and nutrition of the citizens, in South Korea, the elderly, whose average sleep time was less than 6 hours, accounted for 27% [9]. In order to live a healthy aged life, the quality of sleep of the elderly is important. Te quality of sleep varies from individual to individual. Te quality of sleep also becomes diferent with age. As for the characteristics of the sleep of the elderly, although there is no change in the entire sleep time, lowquality sleep can exist [10]. In other words, it takes a long time until falling asleep. In addition, they wake up frequently while sleeping. Once they wake up, they fnd it difcult to fall asleep again. Sleep problems are common among the elderly [11].
Quality of life may be a multidimensional concept that means the subjective sense of satisfaction that each and every individual feels under objective conditions, which means the condition of the well-being physically and mentally [12]. In old age, the quality of life gets lowered in all of the physical, functional, mental, and social domains due to the weakening of the physical functions related to aging and facing a psychological, social, or economic crisis situation [11]. Especially, the depression that appears among the elderly gets connected to the loss of the role and the dependent life [13]. Old age may be a time when there is more role loss than at any other phase in the development of life. During the time of such a loss, the elderly can easily fall into a state of depression. In addition, the worsening of health, bereavement, and economic difculty can also lower the overall quality of life of the elderly. As for the approach to solving the problem of the mental health of the elderly, a general approach is needed in the social, economic, and psychological aspects.
In order to be able to live a healthy and happy aged life, eforts for understanding and supporting are continuously needed [14,15]. As the quality of sleep is infuenced by a psychological aspect such as depression, depression is an important health problem that lowers the quality of sleep.
Depression and the quality of sleep have a big infuence on the health condition of the elderly because they may be important health problems that cannot be overlooked in terms of the quality of life. Terefore, the purpose of this study is to provide basic data for the healthcare of the elderly by investigating the efects of depression and quality of sleep on the lives of the elderly.

Respondents of the Study.
Te respondents of this study were 120 elderly people who used the elderly welfare center and senior citizen center in one of the cities in South Korea, who understood the purpose of the study and signed the consent form for participation in the study.

Research Instruments
2.2.1. Depression. Te Geriatric Depression Scale Short Form-Korea Version, GDSSF-K, which Ki had translated and standardized from the GDS Short Form, which was developed by Sheikh and Yesavege, had been used [16], and with a total of 15 questions, in the case of "Yes," it was 1 point. In the case of "No," it was 0 point. Te higher the score, the greater the extent of the depression. Also, according to the score, 0 point to 4 points is classifed as normal, 5 points to 9 points is classifed as slight depression, and 10 points to 15 points is classifed as serious depression. Among the total of 15 questions, 10 questions were positive questions, and regarding these positive questions, they were reverse converted. Te higher the score, the greater the extent of the depression.
At the time of development, the reliability was Cronbach's α � .94. In this study, the reliability was Cronbach's α � .90.

Quality of Sleep.
In order to measure the quality of sleep, a tool developed by Kwon has been used [17]. Regarding the tool for measuring the quality of sleep, there had been 15 questions. Regarding each question, with the Likert scale of 5 points, it had been organized with the scale from 1 point for "Not at all so" to 5 points for "It is always so." Also, the higher the score, the worse the quality of sleep.
At the time of development, the reliability was Cronbach's α � .89. In this study, the reliability was Cronbach's α � .94.

Quality of Life.
In order to measure the quality of life, the Korean version of the WHOQOL-BREF [18] that had been revised based on the WHOQOL-100, which was developed by the WHO, had been used. Also, regarding this research, with the 8 questions in the domain of physical health, the 6 questions in the psychological domain, the 2 questions in the social domain, and the 8 questions in the living environment domain, it is organized with a total of 24 questions in the 4 domains. Te measurement of each question had been a 5 points scale from "Not at all so" 1 point to "Very much so" 5 points. Also, the higher the score, the better the quality of life At the time of development, the reliability was Cronbach's α � .89. In this study, the reliability was Cronbach's α � .90.

Data Analysis.
Te data of this study were analyzed by using SPSS (ver. 25.0). Te general characteristics such as the level of depression, quality of sleep, and quality of life were analyzed by frequency, percentage, mean, and standard deviation. Te levels of depression, quality of sleep, and quality of life as measured by the general characteristics were evaluated by t-test and ANOVA. Te quality of life, depression, and quality of sleep were analyzed by Pearson's correlation analysis. A linear regression analysis was performed to analyze the factors infuencing sleep quality.

General Characteristics of Subjects.
Regarding the gender, it appeared that the males were 18.3% and the females were 81.7%. Te average age was 74.98 years old. Regarding the academic background, the junior high school graduates or lower were the majority at 73.3%. Regarding religion, Buddhism was the most at 45.0%. Te housemate is the spouse, with the most at 50.8%. Te average number of children was 2.78 persons. Regarding whether or not there are children to rely on, it appeared that "Tere are" was 90.8% and "Tere are not" was 9.2%. Regarding the person who gives help and pays attention at ordinary times, the children were the most at 50.0%. Regarding the number of times the gathering occurred, 1 time or more in two months was the most at 43.3%. Regarding whether or not there is a workplace, it appeared as "Tere is not" at 87.5% and "Tere is" at 12.5%. Regarding the economic level, ordinary was the most at 68.3%, and it appeared in the order of being on the difcult side at 16.7% and on the side of living well at 15%. Regarding the allowance for one month, 300,000 won or less was the most at 32.5%. Regarding the subjective condition of the population's health, ordinary was the most at 46.7%. Also, it appeared in the order of being on the side of being bad at 23.3%, on the side of being good at 21.7%, on the side of being very bad at 4.2%, and on the side of being very good at 4.2%. Regarding whether or not there is an illness, it appeared that "Tere is" was 67.5% and "Tere is not" was 32.5% (Table 1).

Degree of Depression.
As for the degree of depression, the mean of the total score was 3.67. For the question about depression, "Do you frequently feel unrest regarding trivial afairs?" Te score was 0.39, "Are you hopeful regarding the future?" Te highest score was 0.39. On the other hand, "Do you feel that you are happy during most of the time?" scored 0.15, and "Is your mind comfortable like before?" Te lowest score was 0.15 points (Table 2).

Quality of Sleep.
As for the quality of sleep, the average of the total score was 3.85. As for the quality of sleep, "If I wake up while sleeping at night, it is difcult for me to fall asleep again" had the highest score, with 2.53 points, and "I cannot sleep deeply at night" had 2.43 points. Te score of 2.34 for "I cannot fall asleep well even when I am lying down in order to sleep at night" and 2.34 for "Although the time of lying down on the bed is long, the time of actually sleeping is short" was found with a score of 2.34. "Sometimes, I wake up because my legs suddenly tremble or finch while sleeping" was the lowest at 1.60 points (Table 3).

Quality of Life.
As for the quality of life, the average of the total score was 3.54. In all domains, the living environment area had the highest average score of 3.70 points, the psychological domain averaged 3.60 points, the social domain 3.45 points, and the physical domain 3.42 points. In the physical domain, "Satisfed with my capability to carry on with my everyday life" showed the highest score of 3.68. Te lowest score of 3.04 was "A lot of the medical treatment is needed for me to do well in my everyday life." In the psychological realm, "It is not a negative mood, including being depressed, the feeling of despair, the anxiety, the low-spiritedness, etc." It was the highest with 3.81 points. "I accept my physical appearance" was the lowest with 3.39 points. In the social domain, "Satisfed with the help of my friend" showed 3.50 points. "I evaluate the quality of my life as being good" showed 3.49 points. In the living environment area, "I have been living in a residential environment, which is good for health," showed the highest score of 3.93. "I have sufcient money that is needed" showed the lowest score of 3.09 (Table 4).

Depression according to General Characteristics.
In the verifcation of the diference in the degree of depression according to general characteristics, "none" showed the highest score of 4.32 in relation to the number of meeting participations. "Once every 2 weeks" showed the highest score with an average of 4.00, "once a month" with an average of 4.00, and "once a week" with an average of 2.80 points. Tey showed a statistically signifcant diference (p � 0.024). As for the economic level, "economic hardship" was the highest with 5.90 points. "Being ordinary" scored 3.32 points and "pretty rich" scored 2.77 points. Tere was a statistically signifcant diference (p � 0.003). As for the average monthly allowance, "100,000 won or less" showed the highest score with 4.38 points, "300,000 won or less" with 4.02 points, "200,000 won or less" with 4.00 points, and "400,000 won or less" with 3.83 points, "500,000 won or less" with 2.50 points. Tey showed a statistically signifcant diference (p � 0.044). As for the subjective status of health, "very bad" was the highest with 9.20 points, "Ordinary" was 5.10 points, "normal" was 3.10 points, "good" was 2.80 points, and "very good" was 1.0 points in that order. Tis showed a statistically signifcant diference (p � 0.001) ( Table 5).

Quality of Sleep according to General Characteristics.
Regarding the verifcation of the diference in the extent of the sleep resulting from the general characteristic in relation to the question of, "Do you have children who can be relied on?" "Yes" was 3.99 points and "No" was 3.44 points. Tese showed statistically signifcant diferences (p � 0.034). As for the economic level, "high" showed the highest score of 4.08, followed by "medium" at 4.04 and "low" at 3.51. Tere was a statistically signifcant diference (p � 0.005). As for the subjective state of health, "very healthy" showed the highest score with 4.54 points, followed by "healthy" with 4.22 points, "ordinary" with 3.93 points, "very unhealthy" with 3.76 points, and "unhealthy" with 3.49 points. Tey showed a statistically signifcant diference (p � 0.001) ( Table 6).

Quality of Life according to General Characteristics.
Regarding the verifcation of the diference in the extent of the quality of life resulting from the general characteristic, in relation to gender, "female" was 87.11 points and "male" was 80.31 points. Tese showed statistically signifcant diferences (p � 0.005). As for the number of children, "5 persons       Journal of Environmental and Public Health    points. Tere was a statistically signifcant diference (p � 0.010). As for participation recruitment, "the elderly volunteer service organization" showed the highest score of

Conclusions
Te purpose of this study was to provide basic data for the healthcare of the elderly by identifying the efects of depression and quality of sleep on the lives of the elderly. Te summarized conclusions of this research are as follows: the extent of the depression in the subjects was low, with an average total score of 3.67 points; the quality of sleep was low with an average of 3.85 points; and the quality of life had an average of 85.86 points, which was low the medium level.
Te diference in the degree of depression according to the general characteristics was higher as the number of meeting participants decreased, the fnancial difculties increased, the average monthly allowance decreased, and the health status was poor with the depression elderly experienced. As for the diference in sleep quality according to general characteristics, the more children you can depend on, the better the economic level, and the better the health, the better the sleep quality.
As for the diference in the quality of life according to general characteristics, the more children, the more people participating in the elderly volunteer group, the more frequent the meetings, the higher the standard of living, and the higher the allowance for one month. Also, the quality of life of women was higher than that of men.
As a result of this research, diferences in depression, sleep, and quality of life among the elderly according to general characteristics were identifed. Depression, psychological, and social domains had positive correlations, and depression and biological domains had negative correlations.
Sleep quality was found to have a negative correlation with the psychological domain, and sleep quality was found to have a positive correlation with the biological environment domain. Based on this research, this author proposes that research should be attempted later with the elderly who were classifed as the elderly who are living alone, the elderly who are living at home, and the elderly at the facilities as the subjects. In addition, there is a need to develop a continuous, specifc, and practical intervention program that can manage depression and sleep quality in old age.

Data Availability
Te data used to support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that they have no conficts of interest.