Introduction
Aging is a process that occur in all living creatures, including humans [1] and is associated with a set of physical, psychological and social changes which put a heavy burden on psychosocial functioning and mental health of the elderly [2]. One of the common psychological problems in the old age is death anxiety [6, 7]. Death anxiety is a state in which a person experiences anxiety, worry or fear of the death or the process of dying [9]. 
Aging causes a decrease in sleep quality. Poor sleep quality ranks third among the problems of the elderly, after headaches and digestive disorders, and is one of the common complaints and reasons for elderly people to visit doctors [12, 14]. Low sleep quality can increase cognitive impairment in the elderly [18]. Sleep disorder in the elderly may also lead to depression, falls, memory disorders, problems in concentration, excitability, low quality of life, dementia, fatigue, unstable mood, and anxiety [19].
Self-healing practice is one of the popular treatments in the world that helps people to increase relaxation and reduce normal and physiological stress [32]. This approach has five dimensions including physical, psychological, social-communicative, spiritual, and moral-cultural dimension [33]. The ultimate goal of this approach is to increase people's relaxation by training and practicing memory skills, self-help to reduce involuntary responses to irrational fear, and stopping the activity of the brain's fight-or-flight system [34].
Methods
This is a quasi-experimental study with a pre-test/post-test/follow-up design. The study population consists of elderly women living a nursing home in Isfahan, Iran in 2019 with at least a middle school education aged 60-70 years. The sample size was estimated to be 45 based on the minimum required number (n=15) recommended for pilot studies [31] at 95% confidence interval and considering 80% test power. By considering sample dropout, it was reduced to 40. Participants were divided into two groups of training (n=20) and control (n=20).
The data collection tools were the Collett–Lester fear of death scale (CL-FODS) and Petersburg sleep quality index (PSQI). The CL-FODS has 32 questions and four subscales: fear of own death, fear of the process of own dying, fear of the death of others, and fear of the process of others dying. The items are rated on a five-choice Likert scale. To check the reliability of the questionnaire, Cronbach's alpha coefficient was obtained 0.79, indicating its acceptable reliability. The PSQI has 19 items and 7 subscales of subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, and use of sleeping medication, and daytime dysfunction. The items are rated on a five-choice Likert scale from 1 to 5. For the Iranian version of PSQI, the test-retest reliability was obtained 0.86 and the split-half reliability was 0.89.
To analyze the collected data, multivariate analysis of covariance (MANCOVA) was used in SPSS software, version 24. The assumptions of MANCOVA including normality of data distribution and homogeneity of variances were analyzed and confirmed using the Kolmogorov-Smirnov test and Levene’s test, respectively (P>0.05).
Results
The mean age of the participants was 67.97±1.45 years; 3.73% aged 60-64 years, 63.3% aged 64-68 years, and 33.3% aged ≥70 years. Most of the participants had no formal education. Regarding the number of children, 10% had no children, 26.7% had one child, 63.3% had two children. Most of them had a moderate financial status (50%) and only 20% had financial good status. Among the surviving spouses of the participants, 63.3% were over 75 years old. In the training group, all components of death anxiety have improved in the post-test and follow-up phases compared to the pre-test phase, where the highest changes were related to the components of fear of own death and fear of the process of own dying, and the lowest changes were related to the fear of the death of others and the fear of the process of others dying. In the training group, the mean pretest score of death anxiety was 80.90±24.85; it changed to 72.23±25.22 in the post-test phase and 72.76±23.98 in the follow-up phase. In the training group, all components of sleep quality were improved in the post-test and follow-up phases compared to the pre-test phase, where the highest changes were related to the components of habitual sleep efficiency and subjective sleep quality, and the lowest change was related to the component of daytime dysfunction. The mean pretest score of sleep quality was 14.35±4.85 which changed to 11.43±5.22 in the post-test phase and 11.57±4.98 in the follow-up phase.
Discussion
The findings showed that self-healing training reduced death anxiety and improved the sleep quality of older women. It seems that religious beliefs, hoping for intercession by imams and hoping to get rid of the hardships of life had an effect on their low level of death anxiety. Behavioral and spiritual interventions with an effect on finding meaning in the lives of the elderly can reduce death anxiety in the elderly [20]. In a study, it was shown that music therapy can affect sleep quality by distracting mind [38]. It seems that self-healing training, through examining and revising women's life stories and repairing their destructive memories and creating and strengthening healing codes (moral virtues) in them, led to existential development and highlighting their own role and reduced death anxiety and improved sleep quality of older women.
Self-healing training had a significant effect on the components of death anxiety (fear of own death, fear of the process of own dying, fear of the death of others, and fear of the process of others dying). Considering that a realistic and problem-oriented thinking method was taught to the elderly during self-healing training by finding destructive cellular memories, their negative beliefs were identified and corrected. Due to the effect of self-healing on the reduction of destructive cellular memories, the elderly could think less about their past and present bitter memories during sleep, and their false beliefs and negative emotions were corrected and resulted in improved subjective sleep quality. On the other hand, the healing codes, meditation and prayer during the day and especially before going to bed could calm the mind of the elderly and improved their sleep quality. Some of the causes of delay in falling asleep are improper nutrition, poor lifestyle, lack of peace, and destructive cellular memories. Therefore, it seems that self-healing was able to be effective in reducing sleep latency in older women by changing their lifestyle and strengthening their mental and physical health, proper nutrition, and exercise.
The self-healing training is effective in reducing death anxiety and improving sleep quality of older women living in nursing homes who suffered from severe mental and emotional problems, such as the loss of a child or the feeling of loneliness by changing their lifestyle and using spiritual techniques such as praying and communication with God.

Ethical Considerations
Compliance with ethical guidelines
Following the principles of research ethics Ethical principles are fully observed in this article. Participants were allowed to withdraw from the study at any time. Also, all participants were aware of the research process. Their information was kept confidential. Also, all ethical principles have been approved by the Ethics Committee of Payam Noor University and approved with the ethics ID IR.PNU.REC.1400.151.

Funding
This study is based on the master's thesis of the first author in the psychology department of Payam Noor University.

Authors' contributions
Author contributions: Conceptualization, methodology: Laleh Jangi Jahantigh, Zohreh Latifi; Investigation: All Author; Writing-original draft: Laleh Jangi Jahantigh, Zohreh Latifi; Writing-review & editing: All author; Funding acquisition: Laleh Jangi Jahantigh, Zohreh Latifi; Supervision: Zohreh Latifi, Mohammad Soltanizadeh.

Conflicts of interest
The authors declared no conflict of interest.

 

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