Abstract
Objectives
The aim was to determine the effect of shankh (conch shell) blowing on sleep-related outcomes in individuals with moderate obstructive sleep apnoea (OSA).
Methods
This was a prospective open-label randomised control trial with parallel groups including individuals with daytime sleepiness and recent moderate OSA diagnosis. Participants received either intervention of shankh blowing or a sham procedure (deep-breathing exercise) for 6 months. The primary outcome included daytime sleepiness (Epworth Sleepiness Scale; ESS) with two secondary outcomes of sleep quality (Pittsburgh Quality of Sleep Index; PSQI) and the apnoea–hypopnoea index (AHI). Linear mixed-effects models were used to assess outcomes.
Results
Among 30 individuals with moderate OSA, 16 were randomised to the control group and 14 to the intervention group using unrestricted randomisation. Participants in the intervention group had a greater improvement in sleepiness with a 34% reduction in ESS score (change, −5.0 points, 95% CI −8.06– −1.93), and a significant change in the mean difference of the ESS score (−4.69 points, 95% CI −8.39– −1.007; p=0.0145) between groups at the end of the intervention. Sleep quality (PSQI score; change, −1.8 points, 95% CI −3.3– −0.26) and AHI (change, −4.4 events·h−1, 95% CI −7.6– −1.2) were more reduced in the intervention group at 6 months, with a mean between-group difference of −3.1 points for PSQI score and −5.62 events·h−1 for AHI.
Conclusions
The observed improvements in daytime sleepiness, sleep quality and AHI suggest that respiratory muscle training through shankh blowing may emerge as a novel therapeutic option for managing OSA symptoms in the future.
Shareable abstract
This randomised controlled trial showed that respiratory muscle training through shankh blowing reduced daytime sleepiness, improved subjective sleep quality and significantly decreased the apnoea–hypopnoea index in individuals with moderate OSA https://bit.ly/4mOyGU1
Introduction
Obstructive sleep apnoea (OSA) is a widely prevalent sleep disorder characterised by repeated episodes of partial or complete upper airway obstruction during sleep, presenting a significant global public health concern [1–3]. The recurrent nature of pharyngeal obstructions results in intermittent hypoxia and fragmented sleep, leading to excessive daytime sleepiness, poor sleep quality and diminished quality of life [4–6].
Continuous positive airway pressure (CPAP) is widely recognised as the gold-standard treatment for OSA due to its significant efficacy in reducing upper airway obstructions and alleviating associated symptoms when used consistently as prescribed [7–9]. However, despite its proven efficacy, acceptance and adherence to CPAP therapy are often low, presenting a significant barrier to effective OSA management [10–12]. Furthermore, in less-symptomatic individuals, particularly those with mild to moderate OSA, the likelihood of successful treatment outcomes with CPAP is diminished [13, 14]. Consequently, for this subset of individuals not meeting criteria for immediate CPAP therapy, there is a need to explore alternative treatment modalities that are more acceptable and convenient, while maintaining therapeutic efficacy.
For individuals with moderate OSA, available alternative treatments with variable efficacy includes mandibular advancement, weight loss, positional therapy and surgery [15]. Studies have indicated that training or exercising the upper airway muscles, either through playing wind instruments [16, 17] or performing oropharyngeal exercises [18, 19], can improve moderate OSA symptoms. Findings of meta-analysis emphasised respiratory muscle therapy, including playing wind musical instruments, as a potential adjunct management option for OSA [20, 21].
Shankh (conch shell) blowing, a yogic breathing exercise involving forceful exhalation through a conch shell, has been considered to strengthen the oropharyngeal and respiratory muscles and improve lung function [22]. This spiral-shelled device has been used as a musical instrument or decorative piece for centuries. The authors (RG and KKS) observed a subjective improvement in daytime sleepiness among individuals with OSA who were engaged in the practice of shankh blowing. In one case, the author (RG) noted an objective reduction in the apnoea–hypopnoea index (AHI) in an individual who declined CPAP therapy but agreed to perform shankh blowing [23]. The shankh, specifically, Turbinella pyrum or the “Indian Shankha”, possesses a unique spiralling structure with an inner cavity growing both axially and transversely [24–26]. When blown, it produces a resonating sound field believed to hold healing properties [26–28].
The study aims to assess the impact of shankh blowing on subjective daytime sleepiness, subjective sleep quality and AHI in individuals with moderate OSA over a 6-month intervention period. We tested the hypothesis that engaging in respiratory muscle exercises through shankh blowing will result in reduced daytime sleepiness and improved sleep outcomes for individuals with moderate OSA.
Methodology
Study design and participants
The study was a prospective, parallel-group, open-label randomised control trial designed to evaluate the efficacy of shankh blowing compared with a sham procedure (deep-breathing exercises) with monthly follow-up until 6 months. The study enrolled individuals between 19 and 65 years of age presenting with self-reported snoring and daytime sleepiness with a recent diagnosis of moderate OSA evaluated at Eternal Heart Care Centre and Research Institute, Jaipur, Rajasthan, India. Participants with any of the following conditions were excluded from the study: severe symptoms of OSA syndrome that may necessitate CPAP therapy; individuals opting for a mandibular advancement device or surgery; individuals with hypothyroidism, known or suspected significant cardiovascular, pulmonary or metabolic disease; history of stroke, neuromuscular or psychiatric disease; craniofacial malformations or severe obstructive nasal disease (76–100% reduction of total nasal airway space); usage of drugs that act on the central nervous system; current or planned interventions for weight reduction; and a body mass index (BMI) of 35 kg·m−2 or greater.
The study is registered at the Clinical Trial Registry of India (https://ctri.nic.in/Clinicaltrials/; clinical trial number CTRI/2022/04/042225). All participants gave written informed consent before enrolment and the study protocol was approved by the local institutional ethics committee in Jaipur, India (approval number 021/2020). This study followed the Consolidated Standards of Reporting Trials reporting guideline for randomised clinical trials.
Study recruitment, enrolment and randomisation
Participants were recruited from the outpatient unit of the hospital. Prior to enrolment, potential participants underwent clinical and physical examinations and completed baseline measurements to confirm eligibility. The data of the study were collected from 5 May 2022 to 31 January 2024, with a recruitment period from 5 May 2022 to 29 June 2023. A computer-generated simple (unrestricted) randomisation process was used to successively enrol participants to receive either the sham procedure (control group) or the intervention of shankh blowing (intervention group) [29]. Random allocation was conducted by a senior researcher (RG) who was not involved in the assessment process. Considering the nature of the intervention, participants and clinicians were aware of clinical trial group assignments following the randomisation. However, the research personnel (KKS and TS) responsible for data collection and analysis were blinded to group assignments. Furthermore, stringent standardisation procedures were implemented for both data collection and intervention to uphold the internal and external validity of the clinical trial [30].
Study assessments and end-points
Assessments at baseline and at the intervention end-point (6 months) comprised the administration of the Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI) questionnaires, and a full-night polysomnography. The primary outcome of this clinical trial was the change in self-reported sleepiness at 6 months after the intervention. Daytime sleepiness was assessed using the ESS, a subjective eight-item questionnaire that has been validated for people who speak Hindi [31, 32]. Participants rated the likelihood of dozing off in daily situations on a scale from 0 (not at all likely) to 3 (very likely). The total scores on the ESS range from 0 to 24, with higher scores indicating greater sleepiness.
The secondary outcome included changes in subjective sleep quality and apnoea–hypopnoea index (AHI) at 6 months after the intervention. Subjective sleep quality was measured by the PSQI, which assesses subjective sleep quality over the previous 2 weeks and evaluates seven sleep components [33]. PSQI is validated in people who speak Hindi [34]. Participants rated each component on a scale of 0 to 3, with 0 indicating no difficulty and 3 indicating severe difficulty. A global score ranging from 0 to 21 was calculated by summing the subscale scores, with scores above 5 considered indicative of poor sleep quality. The AHI, a measure of the number of apnoea and hypopnoea events per hour of sleep, was objectively measured during a polysomnography. All participants underwent supervised full polysomnography using the following electrophysiological parameters: oral–nasal airflow and pressure via the cannula and thermistor, respiratory effort via the abdominal and chest belts, electroencephalogram (EEG; F4, C4, O2), electrooculogram (EOG), electromyogram (EMG), position detector, arterial oxygen saturation level via the pulse oximeter and heart rate. Recordings were obtained using the Alice 5 diagnostic PSG system (Philips Respironics, USA).
Sleep stages and respiratory events were scored manually by a registered polysomnography specialist, who was blinded to group allocation throughout the trial. Apnoeas were identified as events with a ≥90% reduction in airflow from baseline, lasting at least 10 s, and classified as obstructive, central or mixed, based on the presence or absence of respiratory effort. Hypopneas were scored according to the American Academy of Sleep Medicine (AASM) 2007 Criteria A, defined by a ≥30% reduction in airflow amplitude for a minimum of 10 s, accompanied by a ≥4% drop in oxygen saturation. All scoring was performed in accordance with the AASM Manual for the Scoring of Sleep and Associated Events [35]. Moderate OSA was defined by an AHI ranging between 15 and 30 events per hour of sleep [36].
Study intervention and control conditions
Intervention group
Participants started their shankh blowing training soon after consent, which was given by the instructors (DS and TS). They were provided with a Vamavarta (left-turned) shankh. This is a commonly occurring dextral form of the species characterised by a clockwise spiral when viewed from the shell's apex. The shankh used in this study measured 14 cm in length with an internal diameter of 20 cm (figure 1). During the initial training session, participants were instructed on the proper holding and blowing technique of the shankh. This involved taking a deep inhalation followed by exhalation through the aperture of the shankh. The participants learned to adjust the blowing by controlled breathing techniques to increase the force gradually, allowing for the generation of variable pitches. In the subsequent session (after 1 week), participants further refined their blowing technique. They were instructed to blow with increasing thrust, thereby generating pitches that ranged from low to high frequency. The aim was to achieve a maximum plateau and maintain it for as long as possible, ensuring that vibrations in the upper airway were readily transmitted to the lower airways (see online supplement, which includes a film of the person blowing shankh).
FIGURE 1.
A shankh and a man blowing a shankh.
Participants were encouraged to practice shankh blowing at home for a minimum of 15 min, five days per week. To monitor compliance, all participants were required to maintain a log indicating whether they had performed the intervention (yes or no). Adequate compliance was assessed monthly and defined as performing 80% or more of the proposed blowing sessions. Participants who failed to return for two consecutive months or failed to perform shankh blowing (performing less than 80%) at home were excluded from the study. During each monthly visit, the technique of shankh blowing was reviewed by the instructor, and corrections were made if necessary.
Control group
The control group followed the same schedule and instructions as the intervention group, with the substitution of shankh blowing with a sham procedure involving deep-breathing exercises. Participants were encouraged to practice deep breathing at home for a minimum of 15 min, five days per week, while sitting upright. The breathing involved slow, deep inhalation through the nose followed by relaxed exhalation. Supervised sessions of deep breathing were conducted during training and follow-up visits, and the participants’ logs were reviewed to ensure compliance.
Statistical analysis
The sample size calculation for this study was derived from a comparable trial that used a similar but different intervention [16], where the sd of the difference in ESS between the two groups was calculated to be 2.7 (difference between interventions 3.0; p=0.03, n=25). Assuming a similar sd of 2.7 for our primary end-point, we estimated that enrolment of 28 participants would provide a statistical power of 80% at α=0.05 to detect a minimal clinically significant change of 3.0 for the ESS score. Considering possible dropouts, the recruitment target was set at 38 participants.
All estimations and analyses were conducted using a per-protocol approach, including only participants who completed the intervention and post-intervention assessments as planned. To compare the baseline characteristics of participants based on their assigned groups, we employed unpaired t-tests for continuous variables and Fisher's exact test for nominal variables. For variables with skewed distribution, the Mann–Whitney U-test was used. The primary outcome (subjective sleepiness) was assessed using linear mixed-effects models, with fixed effect for randomisation group, assessment time (baseline and 6 months) and the interaction between groups and time. The secondary outcomes (subjective sleep quality and AHI) and other end-points were analysed using similar mixed models. Estimations were performed using the restricted maximum likelihood method. All statistical tests were two-tailed and statistical significance was set at a p-value <0.05. Statistical analysis of the data was performed using SPSS v.26.0 (IBM Corporation) software.
Patient and public involvement
The participants and public were not involved in the design or reporting of this study.
Results
We screened 62 participants with a recent diagnosis of moderate OSA. Out of these, 38 eligible participants were recruited and randomised, with 19 in each group. Eight participants (five in the intervention and three in control arm) were excluded from the analysis due to low adherence or being lost to follow-up (figure 2). Among 30 participants who completed the follow-up, the mean±sd age was 49.9±13.7 years, the mean±sd BMI was 28.9±4.6 and the mean±sd neck circumference was 39.1±2.9 cm. Among them, 20 participants (66.5%) were male, 10 (33.5%) were current smokers, 14 (47.3%) had a history of hypertension and nine (29.9%) had a history of diabetes mellitus. Baseline sociodemographic, clinical characteristics and sleep-related measures were relatively similar between the intervention and control groups (table 1). There were no adverse or unexpected events in either group.
FIGURE 2.
Participant flow for analyses: Consolidated Standards of Reporting Trials flow diagram.
TABLE 1.
Baseline characteristics of the participants
| Characteristic# | Control | Shankh | p-value |
|---|---|---|---|
| Total participants | 16 | 14 | |
| Age, years | 50.9±14.8 | 48.8±13.2 | 0.697 |
| Males | 11 (68.8) | 9 (64.3) | 0.796 |
| Smoking | 5 (31.3) | 5 (35.7) | 0.796 |
| Hypertension | 6 (37.5) | 8 (57.1) | 0.282 |
| Diabetes | 5 (31.3) | 4 (28.6) | 0.873 |
| Body mass index, kg·m−2 | 29.6±4.3 | 28.2±5.0 | 0.431 |
| Neck circumference, cm | 39.8±3.1 | 38.3±2.7 | 0.179 |
| Sleep efficiency, % | 80.7±5.9 | 81.9±8.9 | 0.661 |
| Lowest SpO2, % | 83.2±5.8 | 80.4±7.4 | 0.268 |
| PSQI, score¶ | 10.7±4.0 | 10.8±3.5 | 0.944 |
| AHI, events·h−1 | 23.8±2.7 | 23.1±3.4 | 0.556 |
| ESS, score+ | 13.9±4.6 | 14.6±5.0 | 0.693 |
Data are presented as mean±sd or n (%). SpO2: oxygen saturation; PSQI: Pittsburgh Sleep Quality Index; AHI: apnoea–hypopnoea index; ESS: Epworth Sleepiness Scale. #: no significant between-group differences were observed in any of the baseline characteristics. ¶: score range, 0 to 21 points, with higher scores indicating worse sleep quality. +: Score range, 0 to 24 points, with higher scores indicating more daytime sleepiness.
Participants in the intervention group experienced a significant improvement in subjective sleepiness (primary outcome), as measured by the ESS. At baseline, the mean ESS score was 14.6 points, which reduced to 9.6 points at the intervention end-point, reflecting a notable 34% reduction (change in ESS score, −5.0 points, 95% CI −8.06– −1.93). No considerable changes in subjective sleepiness were observed in the control group at the intervention end-point (change in ESS score, −0.31 points, 95% CI −1.94–1.31). The mean difference in ESS score change between the intervention and control groups at 6 months was −4.69 points (95% CI −8.39– −1.007; p=0.01) (table 2). Similar results were observed for the secondary outcomes at 6 months of intervention. The participants in intervention group exhibited a significant improvement in the PSQI score (change, −1.8 points, 95% CI −3.3– −0.26) and AHI (change, −4.4 events·h−1, 95% CI −7.6– −1.2) compared with the control group, which showed marginal changes in PSQI score (change, 0.3 points, 95% CI −0.21–2.84) and AHI (change, 1.2 events·h−1, 95% CI −0.48–2.9). The mean difference in change between groups at 6 months of intervention was −3.1 points for PSQI score (95% CI −5.98– −0.21; p=0.03) and −5.62 events·h−1 for AHI (95% CI −9.31– −1.92; p=0.004). Intra-group analysis of proportional AHI changes revealed that, at 6 months, the intervention group experienced a significant reduction in overall AHI, whereas the control group showed a nonsignificant change. Change in AHI, events·h−1 at 6 months (control arm, +5.04%; p=0.147, intervention arm, −19.05%; p=0.011), change in AHI (non-rapid eye movement; NREM), events·h−1 (control arm, +2.02%; p=0.596, intervention arm, −22.83%; p=0.038), change in AHI (rapid eye movement; REM), events·h−1 (control arm, +24.2%; p=0.263, intervention arm, −21.83%; p=0.024). Figure 3 shows individual values for the ESS score in both groups from baseline to 6 months.
TABLE 2.
Primary and secondary outcomes and sleep-related end-points
| Outcome | Control group (n=16) | Intervention group (n=14) | Mean difference between groups# |
|---|---|---|---|
| Primary outcome | |||
| Epworth Sleepiness Scale, score (95% CI)¶ | |||
| Baseline | 13.9 (11.5–16.4) | 14.6 (11.7–17.6) | NA |
| At 6 months | 13.6 (11.0–16.2) | 9.6 (7.2–12.0) | NA |
| Change at 6 months | −0.31 (−1.94–1.31) | −5.0 (−8.06– −1.93)+ | −4.69 (−8.39– −1.007)§ |
| Secondary outcome | |||
| Pittsburgh Sleep Quality Index, score (95% CI)ƒ | |||
| Baseline | 10.7 (8.5–12.8) | 10.8 (8.8–12.8) | NA |
| At 6 months | 12.0 (9.5–14.5) | 9.0 (7.4–10.6) | NA |
| Change at 6 months | 1.3 (−0.21–2.84) | −1.8 (−3.3– −0.26)## | −3.1 (−5.98– −0.21)¶¶ |
| AHI, events·h−1 (95% CI) | |||
| Baseline | 23.8 (22.3–25.2) | 23.1 (21.1–25.1) | NA |
| At 6 months | 25.0 (22.6–27.4) | 18.7 (16.4–21.1) | NA |
| Change at 6 months | 1.2 (−0.48–2.9) | −4.4 (−7.6– −1.2)++ | −5.62 (−9.31– −1.92)§§ |
| End-point | |||
| Body mass index, kg·m−2 | |||
| Baseline | 29.6 (27.2–31.9) | 28.2 (25.3–31.1) | NA |
| At 6 months | 30.1 (27.8–32.5) | 27.9 (25.3–30.5) | NA |
| Change at 6 months | 0.53 (0.10–0.97)§§ | −0.33 (−1.38–0.72) | −0.86 (−4.18–2.46) |
| Neck circumference, cm | |||
| Baseline | 39.8 (38.2–41.5) | 38.4 (36.8–40.0) | NA |
| At 6 months | 40.0 (38.3–41.7) | 37.3 (35.7–38.9) | NA |
| Change at 6 months | 0.15 (−0.33–0.64) | −1.0 (−1.8– −0.30)++ | −1.3 (−3.44–0.84) |
| Sleep efficiency, % | |||
| Baseline | 80.7 (77.5–83.8) | 81.9 (76.7–87.1) | NA |
| At 6 months | 81.8 (78.8–84.8) | 84.8 (80.0–89.5) | NA |
| Change at 6 months | 1.1 (−2.7–4.9) | 2.9 (−2.6–8.3) | 1.8 (−3.55–7.15) |
| Lowest SpO2, % | |||
| Baseline | 83.2 (80.0–86.3) | 80.4 (76.1–84.7) | NA |
| At 6 months | 81.4 (77.7–85.2) | 87.5 (84.2–90.7) | NA |
| Change at 6 months | −1.7 (−5.2–1.7) | 7.1 (2.0–12.1)### | 8.8 (3.65–13.94)¶¶¶ |
| AHI (NREM), events·h−1 | |||
| Baseline | 23.2 (21.1–25.3) | 21.9 (19.1–24.7) | NA |
| At 6 months | 23.7 (21.5–25.8) | 16.9 (14.3–19.5) | NA |
| Change at 6 months | 0.47 (−1.37–2.31) | −5.0 (−9.7– −0.33)+++ | −5.5 (−8.93– −2.06)§§§ |
| AHI (REM), events·h−1 | |||
| Baseline | 28.9 (23.5–43.7) | 36.7 (27.6–44.1) | NA |
| At 6 months | 35.9 (31.3–39.2) | 28.7 (24.3–31.2) | NA |
| Change at 6 months | 7.0 (−6.4–20.4) | −8.0 (−14.6– −1.4)## | −15.0 (−22.7– −7.29)§§ |
NA: not applicable; AHI: apnoea–hypopnoea index; SpO2: oxygen saturation; NREM: non-rapid eye movement; REM: rapid eye movement. #: Derived from a linear mixed-effects model that included study group, time (baseline, and 6 months), and study group×time interaction term as fixed effects and participant as random effect. ¶: Score range, 0 to 24 points, with higher scores indicating more daytime sleepiness. +: p=0.004 for time (baseline×6 month) interactions.
§: p=0.01 for time×study group interactions. ƒ: Score range, 0 to 21 points, with higher scores indicating worse sleep quality. ##: p=0.02 for time (baseline×6 month) interactions. ¶¶: p=0.03 for time×study group interactions. ++: p=0.01 for time (baseline×6 month) interactions.
§§: p=0.004 for time×study group interactions. ƒƒ: p=0.01 for time (baseline×6 month) interactions. ###: p=0.009 for time (baseline×6 month) interactions. ¶¶¶: p=0.001 for time×study group interactions. +++: p=0.03 for time (baseline×6 month) interactions. §§§: p=0.002 for time×study group interactions.
FIGURE 3.
Individual values for Epworth Sleepiness Scale score in both groups from baseline to 6 months. In the control group, the change in Epworth Sleepiness Scale score from baseline to 6 months (from 13.9±4.6 to 13.6±4.9 points) was similar. Epworth Sleepiness Scale score significantly reduced in intervention group at 6 months (from 14.6±5.0 to 9.6±4.2 points; p=0.004). The differences between groups remained significant (p=0.01) at the end of the intervention. Short horizontal lines and bars indicate mean±sd. NS: not significant.
Participants in the intervention group had greater reductions in BMI at the intervention end-point (change, −0.33 kg·m−2, 95% CI −1.38–0.72) than participants in the control group who had significant increase in BMI (change, 0.53 kg·m−2, 95% CI 0.10–0.97). Significant changes were observed at the intervention end-point in the intervention group compared with the control group in neck circumference (change, −1.0 cm, 95% CI −1.8– −0.30 versus 0.15 cm, 95% CI −0.33–0.64), lowest oxygen saturation (change, 7.1%, 95% CI 2.0–12.1 versus −1.7%, 95% CI −5.2–1.7), AHI (NREM) (change, −5.0 events·h−1, 95% CI −9.7 to −0.33 versus 0.47 events·h−1, 95% CI −1.37–2.31), AHI (REM) (change, −8.0 events·h−1, 95% CI −14.6– −1.4 versus 7.0 events·h−1, 95% CI −6.4–20.4). No significant changes were observed in the control group for sleep-related measures at the intervention end-point compared with baseline.
Discussion
Principal findings
This study represents the first investigation into the effects of shankh blowing in individuals with moderate OSA. The findings reveal that a 6-month intervention of shankh blowing resulted in a statistically significant improvement in ESS score, PSQI score and AHI within the intervention group (mean change scores of −5.0, −1.81 and −4.41, respectively). Moreover, when compared with the control group at 6 months, the mean difference of changes in ESS score, PSQI score and AHI were also found to be significant in the intervention group (mean difference score of −4.69, −3.1 and −5.62, respectively). In addition to absolute reductions in AHI, intra-group analysis in the intervention group showed clinically meaningful percentage reductions across both NREM and REM sleep. These reductions exceed the minimal clinically important difference commonly cited in the literature (approximately 20% reduction in AHI), suggesting that the intervention has a meaningful impact on disease severity [12, 37]. As REM-related respiratory events often correlate with greater cardiovascular and neurocognitive risks, the observed 21.8% reduction in REM AHI may translate to important clinical benefits beyond symptom relief.
A significant improvement in lowest nocturnal oxygen saturation (SpO2) was also observed in the intervention group. Although this was not a predefined outcome and was not explored in depth, it may have important clinical implications. Given the established associations between nocturnal desaturation and increased cardiovascular risk in OSA, the observed improvement in oxygenation could indicate an additional therapeutic benefit of the intervention.
The improvement in these outcomes by shankh blowing may be attributed to the training of upper airway muscles, indicating decreased collapsibility of the upper airways. A notable reduction in neck circumference was observed within the intervention group, implying that shankh blowing might induce upper airway remodelling.
Comparison with other studies
To contextualise our findings, we compared the results with previous research on respiratory muscle therapy and musical instrument playing interventions in individuals with OSA. A meta-analysis of various respiratory muscle therapy interventions, including oropharyngeal exercises, speech therapy, breathing exercises and wind musical instruments, in adults with mild to severe OSA, showed an average change of −2.5 units on the ESS score [20]. Similarly, a study involving daily practice of the didgeridoo, a wind instrument, found an average change of −4.4 units on the ESS score [16]. Our study, in line with these previous findings, demonstrated a substantial reduction in subjective daytime sleepiness in the intervention group, with an average change of −5.0 units on the ESS score, affirming that shankh blowing effectively reduces sleepiness. Moreover, the meta-analysis and the didgeridoo study reported average changes in the AHI of −7.6 events·h−1 and −10.7 events·h−1, respectively, and changes in the PSQI score of −1.3 units and −0.9 units, respectively. In our study, the intervention group exhibited an average change in AHI of −4.4 events·h−1 and in PSQI score of −1.8 units compared with baseline. These findings are consistent with the results of previous studies, indicating that participants who engage in shankh blowing experience significant improvements in daytime sleepiness, sleep quality and AHI.
The results from this study align with the findings of previous research, which suggested that training the upper airway muscles, either through playing specific musical instruments [16, 17] or through exercises [18, 19], may provide effective measures to improve sleep-related outcomes and reduce the severity of OSA. There is evidence suggesting that muscle training can reduce the collapsibility of the upper airway during sleep and alleviate sleep apnoea in individuals with OSA [38–40]. Similarly, the practice of shankh blowing may potentially contribute to the training and strengthening of oropharyngeal, lingual and thoracic muscles, which could explain the positive effects observed in the study. Our study revealed a significant decrease in neck circumference in the intervention group compared with baseline. This finding is consistent with previous studies that have shown a reduction in neck circumference as a result of upper airway exercises and potential airway remodelling [18, 19].
Strengths and limitations
The present study describes a novel method to train upper airway muscles by shankh blowing, which significantly improved sleep-related outcomes, for which there is no similar study available to date. The study followed participants over a 6-month period, providing a longitudinal perspective on the effects of shankh blowing. The inclusion of a control group with a sham procedure enhances the internal validity of the findings and helps to isolate the specific effects of the intervention. To minimise confounding, we excluded individuals undergoing any established OSA treatment and with any underlying medical conditions.
Our study has limitations. First, being an open-label trial introduces the possibility of performance bias, where the participants’ and researchers’ knowledge of the treatment assignment may influence their behaviour and responses. We blinded the research personal responsible for data collection and analysis to group assignments, and random allocation was performed by people who were not involved in the assessment process. Second, the intervention was not supervised and evaluated at monthly intervals, so we could not explore the substitution effects due to a lack of information on other exercise and activity. However, we checked the logs and confirmed details of other ongoing interventions at each visit. Third, the use of a per-protocol analytical approach, while appropriate for assessing efficacy among adherent participants, may overestimate the treatment effect and limit generalisability. Future studies employing an intention-to-treat design are warranted to better evaluate effectiveness in real-world settings. Fourth, while the improvement in lowest nocturnal SpO2 observed in the intervention group is promising, the study did not assess comprehensive oxygenation metrics such as the oxygen desaturation index, mean SpO2 or duration of desaturation events. We acknowledge that this as a limitation, and future studies should include a more detailed evaluation of nocturnal oxygenation to better understand the physiological impact and clinical significance of the intervention. Finally, the sample size was relatively small and the trial was conducted at a single centre, which may limit the generalisability of the findings. As this was a proof-of-concept study, it serves as a foundation for more extensive research involving larger and more diverse sample sizes across various settings and populations. Future research with robust designs and larger cohorts will be instrumental in validating and expanding the applicability of shankh blowing as a therapeutic option for individuals with OSA.
Conclusions
In conclusion, upper airway muscle training by shankh blowing improves subjective measurements of daytime sleepiness and sleep quality with improvement in objective measures of severity of OSA. Our research provides novel insights into the potential benefits of shankh blowing as an alternative intervention for individuals with moderate OSA. Further research with larger sample sizes is needed to confirm these findings and explore the underlying mechanisms of shankh blowing in individuals with OSA.
Acknowledgements
We acknowledge our technical staff, Vicky Paul, for allowing us to record and use his image and video for the article; sleep specialist, Shikha Jindal, for interpretation of sleep studies; the trial participants who took part in this research; and consultant, Kishore Mangal, for technical support.
Footnotes
Provenance: Submitted article, peer reviewed.
This clinical trial is prospectively registered with Clinical Trials Registry India (CTRI) as CTRI/2022/04/042225.
Ethics statement: The study was approved by the local ethics committee (021/2020).
Conflict of interest: All authors have confirmed that they have no conflicts of interest to declare.
Supplementary material
Please note: supplementary material is not edited by the Editorial Office, and is uploaded as it has been supplied by the author.
Supplementary video 00258-2025.SUPPLEMENT (23.6MB, mov)
Informed consent form 00258-2025.SUPPLEMENT (136.6KB, pdf)
References
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