Effectiveness of Otago exercise on sleep quality and dialysis adequacy in hemodialysis patients

Abstract

Background

Patients undergoing hemodialysis commonly experience complications such as poor sleep quality and inadequate dialysis efficiency. Therefore, effective nursing interventions are essential to mitigate these issues. This study was conducted with the aim of determining the effect of home-based Otago exercise on sleep quality and dialysis adequacy among patients undergoing hemodialysis in selected hospitals affiliated with Iran University of Medical Sciences in Tehran.

Methods

In this randomized controlled clinical trial, 46 hemodialysis patients were recruited from two dialysis centers in Tehran and randomly allocated into intervention and control groups using block randomization. The intervention group performed home-based Otago exercises three sessions per week for eight weeks, following initial training and regular follow-up. The outcome measures included the Pittsburgh Sleep Quality Index (PSQI) questionnaire and dialysis adequacy indices (Kt/V and URR), which were assessed both before and after the intervention in both groups. Data were analyzed using descriptive and inferential statistical tests through SPSS software version 16.

Results

Out of 45 participants, 44 completed the study. The two groups were demographically homogeneous. After the intervention, the intervention group showed significant improvements in sleep quality (P < 0.001), KT/V (P = 0.002), and URR (P = 0.006). Between-group comparisons also showed significant differences in sleep quality (P = 0.006) and KT/V (P = 0.023), but not in URR (P = 0.693).

Conclusion

Home-based Otago exercise can be used as a safe, low-cost, and effective intervention to improve both sleep quality and dialysis adequacy in patients undergoing hemodialysis. It is recommended that implementation of this home exercise program be taught to patients and followed up regularly.

Trial registration

This trial was registered at the Iranian Registry of Clinical Trials: IRCT20210911052440N1)Date of registration: 2022-02-25) https://irct.behdasht.gov.ir/trial/58681.

Background

The increasing prevalence of chronic diseases, particularly in transitional societies, has become one of the major challenges for health systems worldwide, accounting for approximately two-thirds of global mortality. Among these, chronic renal failure (CRF) is recognized as one of the most common and rapidly spreading chronic conditions [1]. Estimates suggest that about 15% of adults in the United States—equivalent to 37 million individuals—are affected by some degree of this disease [2]. Estimates suggest that approximately 15% of adults in the United States—equivalent to around 37 million individuals—are affected by some stage of this disease [3]. Chronic renal failure refers to a persistent and irreversible decline in kidney function, with its final stage, known as end-stage renal disease (ESRD), requiring replacement therapies such as hemodialysis, peritoneal dialysis, or kidney transplantation [4, 5].

According to statistics from 2016 (Iranian calendar year 1395), approximately 60,000 Iranian patients were undergoing renal replacement therapy, with around 50% of them receiving hemodialysis treatment [6]. Despite the effectiveness of hemodialysis in improving patient survival, this treatment is associated with significant complications, including sleep disturbances [7]. Poor sleep quality is a common complaint among hemodialysis patients and has been linked to a reduced quality of life [8]. In a review study, Mirghaed and colleagues reported poor sleep quality in more than 75% of Iranian hemodialysis patients [9]. Numerous factors, such as urea and creatinine levels, parathyroid hormones, blood pressure, comorbidities, and lifestyle, can contribute to these disturbances. Insomnia in these patients leads to fatigue, irritability, reduced pain tolerance, and cognitive impairments [4].

Another important outcome among hemodialysis patients is dialysis adequacy [10] or effective dialysis dose, which is measured using indices such as Kt/V and urea reduction ratio (URR) [11–13]. These indices are used as clinical indicators to assess the efficiency of dialysis in removing waste products from the body. Among these, Kt/V—which combines urea clearance rate, dialysis time, and urea distribution volume—is generally preferred [14, 15]. According to guidelines issued by the Renal Physicians Association (RPA) and the National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI), the Kt/V value should be at least 1.2 and URR should exceed 65% to be considered adequate dialysis. Later recommendations increased the target Kt/V to 1.4 [16]. Evidence indicates that dialysis adequacy is directly associated with patients’ nutritional status, caloric intake, and general health condition. Inadequate dialysis increases the number of dialysis sessions, imposes higher treatment costs, and prolongs hospitalization days [16]. Various factors, including diet, type of dialyzer, blood flow rate, duration of dialysis, comorbidities, and patient education, may influence dialysis adequacy [6].

Numerous studies have examined both pharmacological and non-pharmacological interventions aimed at improving sleep quality and dialysis adequacy. Within the pharmacological domain, drugs such as Zaleplon [17], melatonin [18], and zolpidem [19] have been identified as effective agents in improving sleep in dialysis patients. However, despite their efficacy, concerns regarding dependency, side effects, and limited access have posed challenges to their widespread use.

In contrast, non-pharmacological interventions—which are generally safer and more accessible—have received increasing attention in recent years. These include sleep hygiene education [20], massage therapy [21], aromatherapy [21], guided imagery [22], dietary modification [23], and especially exercise [24]. Among these non-pharmacological strategies, exercise offers a unique advantage over other methods due to its feasibility at home, low cost, and potential to simultaneously improve physical, psychological, and metabolic aspects of patients’ health. Exercise, as a simple, safe, and effective intervention, holds great potential for improving both physical and psychological outcomes in renal patients. In this regard, Tayebi and colleagues demonstrated the effectiveness of isometric resistance exercises and amino acid supplementation in enhancing dialysis adequacy [25]. Other studies have also shown the beneficial effects of exercise training on improving sleep quality in hemodialysis patients [26, 27].

One specific type of exercise is the Otago home-based exercise program, which was developed by healthcare professionals based on individual tolerance and includes strengthening, balance, and aerobic exercises. This program was first developed and tested at the University of Otago in New Zealand [28]. The Otago exercise program features several advantages, including no need for specialized equipment, step-by-step progression, and ease of implementation. Its effectiveness has been reported in elderly populations and patients with chronic conditions [29, 30].

However, most previous studies have focused on single outcomes, and there is limited research examining both sleep quality and dialysis adequacy simultaneously through structured exercise programs such as Otago, especially among hemodialysis patients. Additionally, limited access to complex and costly interventions in dialysis centers highlights the necessity of designing simple, cost-effective, evidence-based programs. Therefore, considering the high prevalence of sleep disturbances, the importance of dialysis adequacy, the safety profile of non-pharmacological interventions, and the lack of local studies on the impact of home-based Otago exercise in this patient population, the present study was conducted with the aim of investigating the effect of the Otago home exercise program on sleep quality and dialysis adequacy among patients undergoing hemodialysis.

Methods

This study was designed and reported in accordance with the latest recommendations of the CONSORT 2025 statement for randomized clinical trials [31].

Trial design

This study was a quantitative, applied clinical trial designed as a randomized controlled clinical trial with a parallel-group structure and 1:1 allocation ratio. It was registered in the Iranian Registry of Clinical Trials under the code IRCT20210911052440N1. Data collection was conducted over a period of seven months beginning in March 2022.

Participants and setting

Study participants were selected from the dialysis units of two hospitals affiliated with Aja University of Medical Sciences in Tehran, each equipped with at least 20 dialysis stations. Patients received hemodialysis every other day.

The target population consisted of all individuals undergoing hemodialysis at the selected hospitals. Inclusion criteria were: age between 18 and 75 years; undergoing hemodialysis for at least six months; dialysis frequency of at least two sessions per week; absence of acute infection, severe cardiac or respiratory insufficiency, or unknown inflammatory diseases; physical ability to perform exercise movements; and no prior familiarity with the Otago exercise program. Exclusion criteria included unwillingness to continue participation or missing more than three exercise sessions.

Sample size

The sample size was calculated using G*Power software, considering a type I error (α) of 0.01 and a statistical power of 90%, based on the results of a previous study by Shayan et al. (2019) [32]. This yielded a required minimum of 20 participants per group. To account for potential attrition (estimated at 15%), the final sample size was increased to 23 individuals per group, totaling 46 participants. No interim analyses were planned or conducted, and no stopping guidelines were applied. All analyses were performed after completion of data collection.

Randomization and allocation

Participants were initially selected using a convenience sampling method and subsequently randomly assigned to either the intervention (Group A) or control group (Group B) using a four-block randomization method. The six possible allocation sequences used were AABB, ABAB, ABBA, BBAA, BABA, and BAAB. The allocation sequence was implemented by the primary researcher. After generating the block randomization sequence, each allocation was placed in an opaque, light-tight, sealed, and numbered envelope. The envelopes were arranged in numerical order (from 1 to 46). At the time of each participant’s final entry into the study, the envelope corresponding to that participant’s number was opened by the person responsible for sample recruitment and the group allocation was determined. This procedure ensured that the allocation sequence remained hidden until the participant entered the study and that the researcher or intervention administrators did not know the group allocation beforehand. (Fig. 1).

Fig. 1.

The process of study

Blinding

Due to the nature of the intervention, it was not possible to blind participants or those delivering the intervention. However, the statistician was blinded to group allocation by using coded labels for the intervention and control groups (e.g., Group A and Group B). The coding was created and assigned by the principal investigator and the data file was anonymized before analysis. The statistician was not informed of the actual group identities until the completion of all analyses. This method ensured unbiased statistical evaluation of outcomes.

Data collection

The data collection instrument included a demographic characteristics questionnaire with items such as age, gender, marital status, educational level, occupation, duration of illness, duration of hemodialysis, and underlying disease. Underlying diseases were documented as a single binary (yes/no) composite variable in the demographic questionnaire. This variable encompassed major comorbidities including diabetes mellitus, hypertension, cardiovascular disease, respiratory disorders (e.g., COPD), anemia, peripheral neuropathy, and other chronic conditions that could potentially influence sleep quality or dialysis adequacy.

The primary outcome of this study was sleep quality, which was assessed using the Pittsburgh Sleep Quality Index (PSQI) [33]. Developed by Dr. Buysse and colleagues in 1989 at the University of Pittsburgh Psychiatry Institute, the PSQI consists of 14 items grouped into 7 components:

1. Subjective sleep quality (item 9)

2. Sleep latency (items 2 and 5a)

3. Actual sleep duration (item 4)

4. Sleep efficiency (items 1, 3, and 4)

5. Sleep disturbances (items 5b–5i)

6. Use of sleep medications (item 6)

7. Daytime dysfunction (items 7 and 8)

Each component is rated on a scale from 0 (no difficulty) to 3 (severe difficulty). The global PSQI score ranges from 0 to 21, with scores ≥ 5 indicating poor sleep quality [34].

The validity and reliability of the PSQI in the Iranian population have been confirmed. Farhadi Naseb et al. [35] at the Tehran Psychiatric Institute established its validity, and Faraee et al. [36] reported a sensitivity of 100%, specificity of 83%, and a Cronbach’s alpha of 0.98 for the Persian version. Kashani et al. [37], referencing Watson et al., reported a test-retest reliability coefficient of 0.58 after one year in the general population.

The secondary outcome was dialysis adequacy, which was assessed using two indices: Kt/V and Urea Reduction Ratio (URR), calculated based on the Daugirdas II formula as follows:

1

2

Where:

• R = ratio of post-dialysis to pre-dialysis blood urea nitrogen (R = BUN2 / BUN1)

• t = duration of each dialysis session

• UF = ultrafiltration volume

• W = post-dialysis weight

Intervention

Initially, sleep quality and hemodialysis adequacy were assessed in all participants across both groups. For the intervention group, Otago exercise training materials were developed in the form of an illustrated booklet (Table 1).

Table 1.

Otago exercise program taught to Hemodialysis patients

No	Exercise Name	Description	Repetitions / Duration
1	Head Rotation Side-to-Side	Stand upright, look forward, and rotate your head to the right and left	5 times
2	Head Extension Backward	Stand upright, place hands on chin, and tilt the head backward	5 times
3	Back Arching	Stand upright, hands behind back, arch the spine	5 times
4	Trunk Rotation	Stand upright, hands on hips, twist trunk to right and left	5 times
5	Toe Pointing While Sitting	Sit down, point toes up and down	10 s per foot
6	Leg Raises with Weight	Sit down, raise one leg at a time with weight	10 repetitions per leg, 3 sets
7	Knee Bends with Weight	Stand upright, bend knees until heels approach buttocks	10 repetitions per leg, 3 sets
8	Lateral Leg Raises	Stand beside a bench, lift each leg sideways	10 repetitions per leg, 3 sets
9	Heel Raises	Stand upright, rise onto tiptoes and lower back down	20 repetitions
10	Walking on Heels	Walk on heels while keeping toes raised	20 repetitions
11	Partial Squats	Stand upright, slightly bend knees into a partial squat	20 repetitions
12	Backward Walking Holding a Bench	Hold a bench for support, walk backward for 10 steps	3 times
13	Figure-Eight Walking	Walk in a figure-eight pattern at normal pace	8 repetitions
14	Side Stepping	Take 10 side steps to the right and left	3 times
15	Straight-Line Standing	Stand with feet aligned in a straight line, maintain balance	10 s per position
16	Single-Leg Standing	| Stand upright and hold one leg up	10–30 s per leg
17	Walking on Toes or Heels	Walk 10 steps on toes or heels	4 repetitions
18	Straight-Line Backward Walking	Step forward and backward in a straight line, walk backward	20 steps
19	Rising from a Chair with/without Hand Support	Rise from a chair with or without hand assistance	15–20 repetitions
20	Stair Climbing	Climb up and down 5 stairs	5 repetitions

In the intervention group, the Otago home-based exercises were taught face-to-face by the researcher to the patient and their caregiver in the rest area of the hemodialysis unit. The patients were asked to perform the exercises once under the supervision of the researcher to ensure proper technique. Instruction continued until the researcher was fully confident in the patient’s ability to perform the exercises independently.

Participants were provided with an instructional video, the illustrated Otago exercise booklet, and the researcher’s contact information for any questions that might arise during the program. Patients in the intervention group and their caregivers were advised to wear comfortable clothing and shoes during the exercises and to ensure safety—e.g., avoid leaning on unstable objects that may move. Participants were instructed to perform the exercises according to the following schedule: three sessions per week for eight weeks, each session lasting approximately one hour, conducted on non-dialysis days under family supervision [38]. The timing of the exercise sessions was at the participants’ discretion, provided they were performed on non-dialysis days; however, participants were advised to preferably schedule the sessions in the morning and to ensure at least 3–4 hours’ distance from their usual bedtime to minimize any potential interference with sleep onset, consistent with common sleep hygiene recommendations. They were also informed that they could split the exercises into smaller segments rather than performing them all at once. Participants were encouraged to take at least three deep breaths between each exercise and to rest as needed.

It was explained that mild stiffness after the first session is normal, especially if the individual has not exercised before. Continuing the program helps prevent future muscle soreness. In order to prevent injuries, patients were instructed to contact the instructor immediately if they experienced dizziness, chest pain, or shortness of breath (i.e., when unable to speak comfortably due to breathing difficulty) during the exercises.

To ensure adherence and prevent forgetting the routine, the researcher followed up with participants through regular phone calls and in-person visits [39]. Additionally, participants were provided with a structured daily exercise checklist log, consisting of a table listing the 17 Otago exercises with the prescribed repetitions/sets. Participants (or caregivers) marked a tick (✓) for each completed exercise on the scheduled days. These logs were reviewed during telephone follow-ups and in-person visits to verify adherence, identify potential issues, and offer targeted support.

At the end of the intervention period, the Pittsburgh Sleep Quality Index questionnaire and dialysis adequacy measures were reassessed. In the control group, no specific intervention was implemented; only assessments of sleep quality and dialysis adequacy were performed at two time points, separated by eight weeks.

Participants were asked to report any discomfort, pain, dizziness, chest pain, or shortness of breath during the exercise sessions. No specific harms or unintended effects were expected based on the nature of the intervention. Any adverse events were to be documented and reported.

Statistical analysis

Data were analyzed using SPSS version 16. Descriptive statistics (mean, SD, frequency) were used to summarize variables. The Kolmogorov–Smirnov test evaluated normality. Depending on the variable type and distribution, inferential tests including independent t-test, paired t-test, Fisher’s exact test, and Chi-square test were applied. A p-value less than 0.05 was considered statistically significant.

Results

A total of 45 participants were enrolled in the present study. One participant from the control group was withdrawn for unspecified reasons, and the remaining participants completed the study. The mean age of patients was 58.7 years (standard deviation [SD] = 12.0) in the intervention group and 62.4 years (SD = 11.3) in the control group. Additionally, the mean duration of hemodialysis treatment was reported as 24.9 months (SD = 28.4) in the intervention group and 25.8 months (SD = 20.1) in the control group.

The majority of participants in the intervention group were male (69.6%) and married (91.3%). Mann-Whitney U test results indicated no statistically significant differences between the two groups in terms of demographic variables such as age, gender, marital status, educational level, dialysis duration, and other personal characteristics (P > 0.05). Therefore, it can be concluded that the two groups were homogeneous in terms of baseline characteristics (Table 2).

Table 2.

Demographic characteristics of participants in the study

Variable	Group	Intervention (Mean ± SD / n (%))	Control (Mean ± SD / n (%))	Test statistic
				Value	P-value
Age (years)		58.7 ± 12.0	62.4 ± 11.3	t = 1.039	0.305٭
Duration of hemodialysis (months)		24.9 ± 28.4	25.8 ± 20.1	t = -0.114	0.910٭
Hemodialysis session length (hours)		3.53 ± 0.50	3.80 ± 0.39	t = 1.938	0.059٭
Gender	Male	16 (69.6%)	17 (77.3%)		0.738٭٭
	Female	7 (30.4%)	5 (22.7%)
Marital Status	Single	2 (8.7%)	0 (0.0%)		0.489٭٭
	Married	21 (91.3%)	22 (100%)
Education	Below diploma	6 (26.1%)	5 (22.7%)	χ² = 1.63	0.906٭٭
	Diploma	6 (26.1%)	8 (36.4%)
	Associate	7 (30.4%)	7 (31.8%)
	Bachelor	3 (13.0%)	2 (9.1%)
	Master	1 (4.3%)	0 (0.0%)
Occupation	Homemaker	5 (21.7%)	5 (22.7%)	χ² = 6.10	0.270٭٭
	Self-employed	4 (17.4%)	1 (4.5%)
	Employee	4 (17.4%)	1 (4.5%)
	Retired	8 (34.8%)	14 (63.6%)
	Unemployed	2 (8.7%)	1 (4.5%)
	Disabled	1 (4.3%)	0 (0.0%)
Underlying Disease	Yes	22 (95.7%)	22 (100%)		1.000٭٭
	No	1 (4.3%)	0 (0.0%)
Hemodialysis sessions/week	2 sessions	8 (34.8%)	3 (13.6%)		0.165٭٭
	3 sessions	15 (65.2%)	19 (86.4%)
Smoking History	Yes	4 (17.4%)	7 (31.8%)		0.314٭٭
	No	19 (82.6%)	15 (68.2%)
BMI	Underweight	1 (4.3%)	1 (4.5%)	χ² = 1.45	0.834٭٭
	Normal	11 (47.8%)	10 (45.5%)
	Overweight	8 (34.8%)	10 (45.5%)
	Obese	3 (13.0%)	1 (4.5%)
Daily Exercise	Yes	10 (43.5%)	7 (31.8%)		0.542
	No	13 (56.5%)	15 (68.2%)

٭Independent t-test٭٭Fisher’s Exact Test

The mean and standard deviation of sleep quality scores before the intervention were 6.60 ± 3.75 in the intervention group and 5.71 ± 4.12 in the control group. Independent samples t-test revealed no statistically significant difference between the two groups at baseline (P = 0.455). After the intervention, the mean sleep quality score decreased to 3.17 ± 3.35 in the intervention group and 6.47 ± 4.19 in the control group, indicating a statistically significant difference between the groups (P = 0.006). Moreover, sleep quality significantly improved from pretest to posttest within the intervention group (P < 0.001), but no significant change was observed in the control group (P = 0.088) (Table 3; Fig. 2). The between-group effect size (Hedges’ g) for post-intervention sleep quality was − 0.86 (95% CI: -1.47 to -0.24), representing a large effect in favor of the intervention group.

Table 3.

Comparison of mean sleep quality scores between the two groups

Variable	Time	Intervention Group (Mean ± SD)	Control Group (Mean ± SD)	Independent t-test (t, p)
Sleep Quality	Before Intervention	6.60 ± 3.75	5.71 ± 4.12	t = -0.753, p = 0.455
Sleep Quality	After Intervention	3.17 ± 3.35	6.47 ± 4.19	t = 2.898, p = 0.006
Paired t-test	Intervention	p < 0.001	t = 10.965
Paired t-test	Control	p = 0.088	t = -1.793

Fig. 2.

Comparison of mean sleep quality scores between the two groups

Regarding the Kt/V scores, the mean and SD before the intervention were 1.31 ± 0.9148 in the intervention group and 1.29 ± 0.22 in the control group. Independent samples t-test showed no statistically significant difference between the groups at baseline (P = 0.891). Post-intervention scores were 1.46 ± 0.52 in the intervention group and 1.28 ± 0.21 in the control group, showing a statistically significant difference between the two groups (P = 0.023). Furthermore, Kt/V scores increased significantly from pretest to posttest in the intervention group (P = 0.002), while no significant change was observed in the control group (P = 0.821) (Table 4; Fig. 3). The between-group effect size (Hedges’ g) for post-intervention Kt/V was 0.44 (95% CI: -0.15 to 1.03), indicating a small-to-moderate effect in favor of the intervention group.

Table 4.

Comparison of mean KT/V scores between the two groups

Variable		Time	Intervention Group (Mean ± SD)	Control Group (Mean ± SD)	Independent t-test (t, p)
KT/V	Before Intervention		1.31 ± 0.48	1.29 ± 0.22	t = 0.138, p = 0.891
KT/V	After Intervention		1.46 ± 0.52	1.28 ± 0.21	t = 1.587, p = 0.023
Paired t-test	Intervention		p = 0.002	t = -3.488
Paired t-test	Control		p = 0.821	t = -0.229

Fig. 3.

Comparison of mean KT/V scores between two patient groups

The PSQI component 6 (‘Use of sleep medications’) showed low baseline values in both groups, with no significant difference (intervention group: mean ± SD = 0.65 ± 1.27; control group: 0.82 ± 1.30; independent t-test, p = 0.666). Post-intervention, the mean score remained unchanged in the intervention group (0.65 ± 1.27) and slightly increased in the control group (0.90 ± 1.34), with no significant between-group difference (p = 0.523). These findings indicate that the substantial improvement in global PSQI score observed in the intervention group was not accompanied by a reduction in reported.

For URR scores, the mean and SD before the intervention were 63.67 ± 9.40 in the intervention group and 66.00 ± 7.73 in the control group. Independent samples t-test again showed no significant difference between the two groups (P = 0.371). After the intervention, the scores changed to 67.52 ± 8.55 in the intervention group and 66.61 ± 6.21 in the control group. Although there was an increase in URR in the intervention group, the intergroup difference was not statistically significant (P = 0.693). However, within-group analysis revealed a significant improvement in URR from pretest to posttest in the intervention group (P = 0.006), while no significant change was observed in the control group (P = 0.575) (Table 5; Fig. 4).

Table 5.

Comparison of mean URR scores between two patient groups

Variable		Time	Intervention Group (Mean ± SD)	Control Group (Mean ± SD)	Independent t-test (t, p)
URR	Before Intervention		63.67 ± 9.40	66.00 ± 7.73	t = 0.904, p = 0.371
URR	After Intervention		67.52 ± 8.55	66.61 ± 6.21	t = 0.397, p = 0.693
Paired t-test	Intervention		p = 0.006	t = -3.025
Paired t-test	Control		p = 0.575	t = -0.570

Fig. 4.

URR score comparison between groups

The between-group effect size (Hedges’ g) for post-intervention URR was 0.12 (95% CI: -0.47 to 0.70), indicating a negligible effect size, consistent with the non-significant between-group difference.

Discussion

This study was conducted with the aim of determining the effect of home-based Otago exercise on sleep quality and dialysis adequacy among patients undergoing hemodialysis. The results indicated a statistically significant improvement in sleep quality in the intervention group compared to the control group, while no notable changes were observed in the control group.

These findings are consistent with those of previous studies. For instance, Theodorou et al. investigated the impact of physical activity on sleep quality in patients with end-stage renal disease undergoing hemodialysis in Greece and reported improvements in sleep quality [27]. Similarly, Mehta et al. from India conducted a single-group intervention study and concluded that an exercise program, as a non-pharmacological approach, effectively improved sleep quality in hemodialysis patients [26]. Maniam et al. also found that a 12-week thrice-weekly exercise program significantly enhanced sleep quality among hemodialysis patients [40]. In an Iranian context, a study demonstrated that hatha yoga had a positive effect on the sleep quality of hemodialysis patients [41].

Exercise improves sleep quality through multiple mechanisms. These include the release of endorphins, which can reduce stress and anxiety, thereby promoting relaxation and better sleep; the regulation of circadian rhythms; and the increase in body temperature followed by its gradual decline, which facilitates the onset of sleep [42]. Additionally, physical activity stimulates the release of neurotransmitters such as serotonin and norepinephrine, which play a role in mood regulation and may help initiate and maintain better sleep [43].

Notably, the Otago exercise program did not lead to a reduction in self-reported use of sleep medications (PSQI component 6), which remained low and stable in the intervention group. This suggests that the beneficial effects on sleep quality were primarily mediated through improvements in other domains (e.g., sleep latency, duration, and disturbances) rather than decreased reliance on pharmacological aids. The relatively low baseline use of sleep medications in our cohort (mean scores < 1.0 in both groups) may have limited the potential to detect changes in this component.

The results also showed a statistically significant increase in the Kt/V index in the intervention group after implementation of the exercise program, and the difference between the two groups was significant post-intervention. This finding aligns with studies such as Kirkman’s review and the research by Paluchamy and Vaidyanathan from India, which confirmed the positive effects of exercise performed during dialysis on improving dialysis adequacy [44, 45]. One possible explanation for this improvement is that exercise increases blood flow and perspiration, aiding in the excretion of waste products through the skin and enhancing filtration rates.

However, no statistically significant difference was observed between the groups regarding the URR index after the intervention. This may be attributed to differences in the sensitivity of these indices or limitations related to sample size.

Conclusions

Overall, the findings of the present study indicate that home-based Otago exercise—being a simple, cost-effective, safe, and easily implementable intervention—can significantly improve both sleep quality and dialysis adequacy indices in hemodialysis patients. These findings support the study’s hypotheses and can be utilized in planning nursing interventions and enhancing care services for chronic patients. One of the key advantages of the Otago exercise program is its home-based nature, which allows patients to perform the exercises independently without the need for specialized equipment or clinical supervision. This feature makes it particularly suitable for individuals with chronic conditions who may face logistical or physical barriers to attending in-person exercise sessions.

One limitation of this study was the relatively small sample size and the fact that it was conducted at only two treatment centers, which may limit the generalizability of the results. Additionally, due to the home-based nature of the intervention, the participants’ adherence to the exercise regimen could not be strictly monitored. The use of self-reported data for some variables may have introduced potential bias. Also, this study did not include any pre-specified or post hoc subgroup or sensitivity analyses. Future studies with larger sample sizes are encouraged to explore potential subgroup differences or assess the robustness of findings through sensitivity analyses. Other limitation of this study is the use of a broad composite binary ‘underlying disease’ variable rather than individual reporting of major comorbidities. Although this approach confirmed overall baseline similarity between groups, it precludes evaluation of potential subtle differences in specific high-impact conditions (e.g., diabetes mellitus, hypertension, cardiovascular disease, COPD, peripheral neuropathy, or anemia), all of which are well-established confounders of sleep quality in hemodialysis populations. Future studies should prioritize the collection and separate reporting of detailed comorbidity profiles, ideally using validated indices such as the Charlson Comorbidity Index (CCI), to allow for more precise confounding adjustment and subgroup analyses. A further limitation of this study is that the prevalence of Obstructive Sleep Apnea Syndrome (OSAS/OSA) was not formally assessed in either the intervention or control group. Although general sleep disturbances were captured through the Pittsburgh Sleep Quality Index (PSQI), including items related to nocturnal breathing discomfort, these components do not enable a formal diagnosis or reliable estimation of OSA prevalence. Validated screening tools (e.g., STOP-BANG questionnaire or Epworth Sleepiness Scale) or objective diagnostic methods (e.g., polysomnography) were not employed, as OSA assessment was beyond the predefined scope and primary outcomes of the trial. Given the well-documented high prevalence of OSA in hemodialysis populations (commonly reported in the range of 50–60% in systematic reviews and meta-analyses) and its potential impact on sleep quality, cardiovascular risk, and overall outcomes, this represents an important limitation. Future studies investigating sleep interventions in hemodialysis patients should incorporate standardized OSA screening or diagnostic tools to better account for this highly prevalent comorbidity.

Future studies should involve larger samples and multiple centers, and employ more precise tools to monitor intervention compliance. Investigating the long-term effects of the Otago program, its impact on other psychological and physiological outcomes in renal patients, and comparisons with other intervention methods could serve as valuable directions for further research.

Abbreviations

ESRD

End-stage renal disease

URR

Urea reduction ratio

RPA

Renal physicians association

NKF-DOQI

National kidney foundation dialysis outcomes quality initiative

PSQI

Pittsburgh sleep quality index

Kt/V

Dialysis adequacy index where K is urea clearance, t is dialysis time, and V is urea distribution volume

BUN

Blood urea nitrogen

SD

Standard deviation

BMI

Body mass index

Author contributions

All authors contributed to the study conception and design. [EA, HB] conducted the data collection, performed the intervention, and drafted the manuscript. [EA] supervised the study process and contributed to data interpretation and manuscript revision. [AP, NR] provided methodological guidance, statistical analysis support, and critical revision of the final draft. All authors read and approved the final version of the manuscript.

Funding

This research was supported by the Aja University of Medical Science.

Data availability

Datasets are available through the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Aja University of Medical Sciences under code IR.AJAUMS.REC.1400.110. The principles outlined in the Helsinki Declaration were strictly followed throughout the study. Participation was entirely voluntary, and individuals could withdraw from the study at any time. Written informed consent was obtained from all participants. Confidentiality of all collected data and ethical use of information sources were ensured. Additionally, the publication ethics guidelines set forth by the Committee on Publication Ethics (COPE) were adhered to throughout the research process.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.