3.1 Elderly patients are prone to sleep disorders
In the present study, the male to female ratio was 1.3:1 and the mean age of the patients was 61.91±13.67 years, similar to previous studies. It was confirmed that older patients are prone to sleep disorders, which may be influenced by the higher accumulation of toxins in one patient, while most patients suffer from other co-morbidities that can directly affect their sleep quality. Middle-aged and elderly patients accounted for 84% of the patients, indicating an overall older age in this group. The number of secondary schools and above was 237, accounting for 89.5%, indicating that the study group had a high level of education. The percentage of non-working people was 81.7%, which shows that most of the patients were over retirement age, and of course, some young and middle-aged patients with poor health conditions were included. Those with a household income of more than 4000 yuan accounted for 55.6% and had a high standard of living. Those with low hemoglobin accounted for 31.7%, indicating that patients had some degree of anemia.
Among 268 patients, 66 patients had glomerulonephritis, 71 patients had hypertension, 60 patients had diabetes mellitus, and 71 patients had other types of diseases, and most of the ESRD patients in this study belonged to the three high groups and were in poor physical condition. Patients with dialysis age of more than 6 years accounted for 78.7%, indicating that patients suffered from a long-term illness. There were 219 patients with autologous arteriovenous endovascular fistula, and 29 patients had emergency or hospitalization experience within the hospital. Taken together, the etiology of the patients is complex and may be related to family genetics or to long-term drug use that damages the kidney.
3.2 Age of dialysis as a risk factor for patient sleep quality
The individual components of the Pittsburgh Sleep Quality Index questionnaire, in order of the percentage of those with perfect scores, were delayed sleep onset (30.6%), hypnotic medication (18.0%), sleep efficiency (14.9%), sleep duration (11.6%), daytime dysfunction (11.2%), perceived sleep quality (7.8%), and sleep disorders (6.0%). Their corresponding sleep problems were, in order, difficulty falling asleep, need for sleeping pills, low sleep efficiency, sleep duration not meeting their needs, poor daytime functioning, and poor conscious sleep quality, but the sleep disorder component was relatively low in severity in this study.
Chinese literature reported that more than 89% of ESRD patients were treated with hemodialysis and sleep disturbance was very common in maintenance hemodialysis patients [9] . In the present study, the author found that 42.16% of MHD patients had poor sleep quality, which was lower than the findings of KRAUS and Wu Y et al [10-11] . Wu MJ et al [12] showed that female patients had poorer sleep quality than male patients. However, in the present study, gender did not correlate with sleep quality (P > 0.05). This may be related to the fact that male patients, as the breadwinners of their families, have increased life stress, complex interpersonal relationships, and need to bear more social responsibilities and family burdens.
The results of this study showed no correlation between the age of MHD patients and their sleep quality (P > 0.05), which is not consistent with the study of Lu Meisu and Zhang Min et al [13-14]. However, the results of the study showed that the longer the age of dialysis, the worse the sleep quality of the patients. This may be due to the fact that as the number of dialysis years increases, patients experience signs and symptoms of secondary diseases in addition to the primary disease as well as hemodialysis treatment, such as renal bone disease, secondary hyperparathyroidism, malnutrition, and pain and discomfort can have a negative physiological and psychological impact on patients, which can lead to a decrease in sleep quality. At the same time, with the increasing number of dialysis sessions, some patients may feel heavy due to the financial burden, and this great psychological pressure is also one of the important factors leading to sleep disorders in patients [15] . Terzi [16] et al. showed that adequate dialysis can improve the sleep quality of patients; GU [17] showed that hemodialysis combined with hemoperfusion can improve sleep disorders in patients and also can promote melatonin secretion in patients and improve sleep quality. Therefore, patients' sleep quality can be improved by giving them different hemodialysis treatment plans.
3.3 Effect of employment status on patients' sleep quality
Different levels of education reflect, to some extent, the occupations in which they are employed, and the occupations differ in terms of their economic capacity, social activities and lifestyles [18].. The results of this study showed that MHD patients who were employed had higher sleep quality than those who were not employed ((OR=0.56, 95% CI (0.35, 0.89)), i.e., being employed was a protective factor for sleep quality in MHD patients. This result suggests that MHD patients may have a high workload and require more mental activities because of their jobs, and may not have time for lunch break during the day; also, the patients are more educated and can cope better with the adverse factors affecting sleep quality through the knowledge about hemodialysis and sleep. The results of this study suggest that health education on psychological care as well as knowledge of sleep etc. should be strengthened for non-working MHD patients, and patients should be encouraged to perform appropriate mental activities and reduce daytime sleep time in order to improve their sleep quality.
3.4 No emergency/inpatient experience in the last month as a protective factor for patient sleep quality
Patients with MHD may require hospitalization for treatment of hyperkalemia, heart failure, and complications or unexpected injuries, such as fractures. The results of this study showed that no emergency/hospitalization experience in the last month (OR=0.41, 95% CI (0.27, 0.70)) was a protective factor for sleep quality in MHD patients. This may be because patients are prone to a strong sense of isolation due to the unfamiliarity of the hospitalization environment and the lack of family companionship and care; one study [19] pointed out that most maintenance hemodialysis patients have difficulty falling asleep, shallow sleep, easy awakening, difficulty in falling back asleep after waking, and the poor mental status during the day. The need to perform some therapeutic care operations on time during hospitalization and the different working hours of patients in the same ward can seriously affect sleep quality and psychological mood. This result suggests that medical staff should strengthen the assessment of patients' conditions and instruct patients to seek medical consultation and treatment promptly if they have discomfort, to reduce the chance of hospitalization and emergency treatment for patients.
In conclusion, the overall sleep quality of MHD patients remains poor, which is related to the patient's dialysis age, work status, and the last 1-month emergency/hospitalization experience. The occurrence of sleep disorders in dialysis patients is the result of multiple factors, including the progression of the patient's primary disease, lifestyle habits, psychological factors, comorbidities, ion metabolism disorders, and toxin accumulation. In contrast to the above factors, hemodialysis treatment itself can have an impact on the quality of patients' sleep. Therefore, medical workers should develop a reasonable dialysis plan in conjunction with the patient's condition to ensure the adequacy of dialysis, so that dialysis patients can obtain the maximum benefit from dialysis treatment, reduce the occurrence of complications, and reduce the impact of sleep disorders induced by hemodialysis treatment. The psychological status of patients should also be closely monitored and early intervention should be made after abnormalities are detected. Strengthening protective factors for sleep quality in MHD patients and taking measures in advance to minimize the risk of sleep disorders as much as possible can help reduce the occurrence of sleep disorders in patients. A study [20] confirmed that by enhancing patients' understanding of their situation and mastering relevant health knowledge, patients' psychological stress can be relieved, thus improving sleep quality. Therefore, health care professionals can provide targeted psychological care and health education to MHD patients, can provide comfort care for them, encourage patients to reduce daytime sleep time, perform appropriate physical exercise according to their physical strength, reduce loneliness, discomfort, and other pessimistic emotions can take hemodialysis treatment combined with conventional hemodialysis to reduce large molecule toxins in patients' bodies, reduce skin itching, improve bone pain, etc. Adjust the dialysis mode to improve the quality of sleep and improve the quality of life of patients.