Introduction
Aging is a psychological process that begins with birth and continues throughout life [1].  Increased life expectancy and a growing older population have been among the achievements of the 21st century. Aging is a phenomenon that human societies have encountered or will encounter [2]. About 60% of older people live in developing countries. This figure is predicted to increase largely by 2050 [3]. The impact of the increasing elderly population has had different consequences on various social and economic dimensions, including the resources for health care [4]. Aging is a critical period in a person’s life in which the function of organs decreases [5] and puts them at risk for disease and illness [6]. Therefore, healthcare providers, including nurses, must be able to identify the needs of the elderly and meet their requirements [7].
Restless leg syndrome (RLS) is a condition that causes an uncontrollable urge to move legs, usually because of an uncomfortable sensation. RLS is accompanied by pain, tingling, and numbness and is exacerbated by rest and inactivity, especially at night [8]. Although the prevalence of RLS in the general population is about 2%-15% [9], the prevalence and severity of the symptoms of RLS increase with age, as it has been reported to be up to 35 % in the older adult population [10]. The RLS has many complications, such as poor quality of life, sleep disorders, high risk of cardiovascular disease, and maybe depression [11].
Sleep is one of the basic human needs and an important part of life [12]. Adequate sleep is necessary for conserving energy and physical and psychological well-being [13]. Sleep disorders occur at any age [14]; however, in the elderly, changes occur in the quality of sleep and circadian rhythms [15]. Some research has shown that poor quality sleep is the third most common cause of aging problems after headaches and digestive disorders, so about 35% of people over 60 do not have adequate sleep quality [2]. Sleep disorders in the elderly include apnea, periodic leg movements during sleep, RLS, insomnia, waking up early in the morning, and the need for daily naps [16]. Sleep disorders affect human health, cognitive function, level of concentration, and a person’s ability to engage in everyday activities. The risk of depression and anxiety increases, and the ability to cope with stressful situations decreases [17]. Sleep disorders are also closely associated with changing mental states, increased mortality, and decreased life quality [18]. Quality of life is defined as the satisfaction of the person from life [19]. Therefore, paying attention to sleep quality is very important [20]. One of the leading causes of sleep disorders, especially in the elderly, is RLS. 
The foundation of treatment of RLS is based on pharmacological and nonpharmacological therapies, and the goal is to eliminate the symptoms and reduce the adverse effects of this syndrome. However, the medication can be accompanied by unpleasant side effects [21, 22]. One of the common treatment methods for musculoskeletal pain relief is the use of heat. Heat treatment raises skin temperature, which dilates capillaries and increases blood flow to the area [23]. Providing heat therapy increases blood flow to a specific location and improves circulation. Vasodilation facilitates healing through an enhanced supply of nutrients and oxygen and removes pain-inducing mediators produced as a by-product of tissue damage [24, 25]. Various forms of heat therapy are used to improve a variety of musculoskeletal disorders [26]. It seems that nurses traditionally apply heat, cold, and some types of massage to reduce pain, but it is necessary for them to present and document the effectiveness of these interventions with scientific evidence. They also state that the methodological evidence for using heat and cold, especially chronic pain, is limited [27]. Considering the significant prevalence of RLS and the high prices of prescription drugs for relief of this syndrome and its numerous complications, this study was performed to determine the effect of a hot water bag on the severity of RLS and sleep quality (SQ) in the elderly.
This study was a quasi-experimental study using experimental and control groups in 2021. The sample size was estimated at 44 for each study group using this formula considering S1=1.41, S2=1.7, µ1=1.4, µ2=2.4, the significance level of 0.05, and a subject attrition rate of 10% (Equation 1). 


 The samples were selected by the purposive sampling method. The elderly with RLS who met the inclusion criteria and consented to participate in the study were selected. Then, 88 older people were randomly assigned to the two groups using computer-generated random numbers. The inclusion criteria were as follows: having at least a moderate level of RLS, aged over 65 years, normal neurological and vascular status, without major musculoskeletal disorders that impair physical activity, and no wounds and redness of the limbs. The exclusion criteria were as follows: insensitivity to heat and the presence of a catabolic process such as cancer, diabetic neuropathy, unconsciousness, use of opioid medications and psychotropic drugs, alcohol abuse, neuromuscular disorders and arthritis under treatment, and the use of hot or cold water bags by the older people at home at the beginning of the study. Also, unwillingness to continue cooperation, dissatisfaction with the intervention and incidence of skin reactions during the study were other exclusion criteria. Elderly participants in the study were selected from two comprehensive health centers in Yazd Province, Iran.
All eligible elderly people were invited to the study through the comprehensive community health centers by phone. In the experimental group, during a routine visit to health centers, the elderly and their caregivers were instructed to use a hot water bag and ROTHO bath thermometer. They were required to have the hot water bag used at a temperature of 40°C-43°C, 1/3 to 2/3 of which was filled on muscle on the front and back of the lower leg. Then, both bags were covered with a towel. The temperature of the bags was measured with a bath thermometer. Researchers in health centers or caregivers assessed after 10 minutes of using the bags the condition of the skin and the reaction of the older in health centers or at home, and in the presence of pain, redness, and swelling, the bags were removed. The duration of using bags was considered 20 minutes based on the textbook of fundamental nursing [28]. The hot water bag was used for 4 weeks, once a day, for 20 minutes at home. The control group received routine care in health centers.
The data collection tool was a demographic questionnaire of elderlies, including gender, age, marriage, and level of education. The second questionnaire was related to the RLS based on the international RLS severity scale. The scale consisted of ten items on a 5-point Likert scale since each item had 0 to 4 points (very severe, severe, moderate, mild, none). The severity of symptoms was classified into five categories based on the obtained points: no problem (0), mild (1-10), moderate (11-20), severe (21-30), and very severe (31-40) [29]. Meharaban et al. examined the validity using the content validity method and reliability by Cronbach alpha of 0.97 [30]. 
Methods
The third part of the questionnaire was the Pittsburgh Sleep Quality Index (PSQI), developed by Boyce et al. in 1989. This questionnaire assessed the quality of sleep over the past month. It has 9 items. Item 5 has 10 sub-categories that provide a general description of SQ, sleep delay, useful sleep duration, the ratio of useful sleep duration to the total time spent in bed, sleep disorder, and waking up due to the shortness of breath, nocturnal cough, body aches, extreme cold, extreme heat, use of sleeping pills to fall asleep, drowsiness, and inability and non-motivation to exercise during the day caused by insomnia. All 19 items were given three types of scores to score the PSQI. Getting a total score above 5 in the whole PSQI means poor SQ [31]. The PSQI is a standard tool for assessing sleep quality over the past month. The validity and reliability of the PSQI have been confirmed in several studies. Buysse et al. stated the internal validity of 0.83 and the reliability coefficient in the re-test to be 0.85 [32]. Parker et al. also described a sensitivity of 90% and specificity of 87% [33].  Bertolazi et al. declared a reliability coefficient of 0.82 with high validity [34]. Also, Hosseinabadi et al. in Iran reported the reliability of the PSQI as equal to 0.88 [35]. The researcher completed the questionnaires through in-person interviews one week before and one month after the study.
Data were analyzed by SPSS16 using descriptive statistics, including mean, standard deviation, frequency, and percentage. The inferential statistics were conducted using the paired t test and independent t test. The normality of data distribution was determined using the Kolmogorov-Smirnov test (P= 0.05). 
The Ethics Committee of Shahid Sadoughi University of Medical Sciences in Yazd, Iran, approved this study with the ethical code: IR.SSU.REC.1397.089 on October 23, 2018. Informed written consent was obtained from the elderly, and no fees were imposed on the participants.
Results
This study was performed on 88 elderly people. Four subjects in both groups were excluded from the study due to a lack of cooperation or unfinished questionnaire completion. Finally, the analysis was performed on 80 participants. The experimental and control groups were all married, and the Mean±SD age of the experimental group was 69.34±4.34 years, and that of the control group was 70.53±5.51 years. There were no significant differences in demographic characteristics using the independent t test and Chi-square test (Table 1).


Based on the findings, the mean score of RLS in the experimental and control groups was not significantly different in the pretest (P=0.32). The mean score of RLS was significantly different in the experimental and control groups in the posttest (P=0.0001). In addition, the mean score of RLS in the experimental group was significantly different in the pretest and posttest (P=0.0001). The mean score of RLS in the control group was not significantly different in the pretest and posttest (P=0.21) (Table 2).


Other findings showed that the mean score of SQ was not significantly different in the experimental and control groups in the pretest (P=0.76). The mean scores of SQ were significantly different between the experimental and control groups in the post-test (P=0.0001). Also, the mean score of SQ was significantly different in the experimental group in the pretest and post-test (P=0.0001). The mean scores of SQ were not significantly different in the control group in the pretest and post-test (P=0.76) (Table 3).


Discussion
This study was performed to determine the effect of hot water bags on the severity of RLS and SQ on 80 elderly people in the experimental and control groups. The majority of women were illiterate, and the average age of the participating older adults was in the range of 65-75 years. All participants were married, and the majority of them used analgesics.
 In the experimental group, the mean score of RLS was moderate before the intervention but changed to a mild level after the intervention with a significant difference. However, the severity of RLS was moderate in the control group before and after the study, with no significant difference. The severity of RLS showed significant differences between the experimental and control groups after the study. No similar studies were found in the literature. However, Nasiriani and Eftekhari (2016) suggested the use of hot water bags as an effective, safe, low-cost method and especially with the ability to be used by patients and their families to relieve the symptoms of restless legs of hemodialysis patients [36]. Jafarimanesh et al. (2020) showed that the intervention with hot water could be used to improve the sleep quality of pregnant women [37]. Yildirim et al. (2010) showed that using heat for one day reduces pain and disability in patients with osteoarthritis of the knee [38]. Lakotaei et al. (2008) in Thailand reported a reduction in pain scores during the first two days of the hot herbal compress group with a statistically significant difference and a  faster effect than the other two groups [39]. Another study evaluated water use (both hot and cold) in 80 pregnant women with anemia problems and  showed good results [40]. According to the findings of the above study and other studies, the use of heat therapy can reduce the severity of restless leg syndrome.
Other results showed that the mean sleep quality score was significantly poor before the study in the experimental and control groups. Nevertheless, after the intervention, according to the interpretation of the PSQI in the experimental group, the SQ of the elderly was still poor but significantly improved. SQ was significantly poor in the control group before and after the study, and no difference was observed. However, a significant difference was found between the experimental and control groups regarding SQ after the intervention. Although no similar studies were found in the literature, in this context, Dadashpour et al. (2013) reported a significant difference in SQ scores in the posttest in the experimental and control groups after a period of water exercise in male elders [41]. Also, Nasiri et al. (2015) showed that foot baths and reflexology improve SQ in the elderly [42]. Therefore, the findings of this study confirmed that previously using a hot water bag can reduce the severity of restless leg syndrome and improve the quality of sleep. Heat therapy can reduce or eliminate symptoms of RLS and improve SQ.
One of the limitations of the present study was the inability to blind the research and the specificity of the interventions. Another limitation was the lack of knowledge of the accurate use of the hot water bag by the elderly at home, which was beyond the researcher’s control. In addition, another limitation was the lack of objective data (such as polysomnography) to exclude other sleep disorders or to evaluate the concomitant presence of Limb Movement Disorders (PLMS) associated with RLS in a high percentage of cases. Another limitation was that of not having carried out blood chemistry tests with the evaluation of the iron status. A possible condition of anemia, often associated with RLS, could induce different thermoregulation in patients.
Conclusion
Using a hot water bag significantly reduced the average severity of RLS and improved SQ. Since relieving an older person’s pain and discomfort is one of the main tasks of healthcare workers, it is necessary to use such interventions that are cheap, easy, available, and acceptable to older adults and are convenient for patients with RLS. 

Ethical Considerations
Compliance with ethical guidelines
This study was carried out in accordance with the Declaration of Helsinki. This research was approved by the Ethics Committee of Shahid Sadoughi University of Medical Sciences and Health Services; Yazd (IR.SSU.REC.1397.089) on  October 23, 2018. The informed written consent forms were obtained from all participants.

Funding
This study was supported by a grant from Shahid Sadoughi University of Medical Sciences (6037) Yazd, Iran.

Authors' contributions
Contributed equally to the design and implementation of the research: Hojjat Azizkhani, Hossein Nazmieh, and Khadijeh Nasiriani; Contributed to the analysis of the results and writing of the manuscript: Arefeh Dehghani; Contributed to the implementation and data acquisition of the research: Hojjat Azizkhani; Were fully accountable for ensuring the study’s accuracy and had read and approved the final manuscript: All authors.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors express their gratitude to the authorities of Shahid Sadoughi University of Medical Sciences. Also, we thank the officials and staff of the comprehensive community health centers and the elderly participating in the study.



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