Yoga nidra practice shows improvement in sleep in patients with chronic insomnia: A randomized controlled trial

INTRODUCTION

Cognitive behavioural therapy for insomnia (CBTI) remains an effective non-pharmacological treatment in patients with chronic insomnia. Although CBTI is considered beneficial, it remains underutilized,¹ primarily because of the cost and increased time of treatment. Most peripheral centres cannot offer CBTI because of lack of trained workforce and financial constraints.

Many therapies have been tried for insomnia such as acupuncture, Kundalini yoga,² Tai Chi Chi,³ mindfulness meditation⁴ and Chinese herbal medicines. Yoga nidra is an ancient technique that sages used to sleep. The method of doing yoga nidra was taught from guru (teacher) to shishya (disciple) and was not documented until the 1960s when a teacher from the Bihar School of Yoga, Munger, Bihar, India, enumerated the method to practice yoga nidra for novices. He described yoga nidra as a ‘systematic method of inducing complete physical, mental and emotional relaxation achieved by turning inwards, away from outer experiences’.⁵ He wrote instructions in a simple form and the practice can be done following instructions from his book. Copyrighted audio CDs are also available. The practice is taught to novices during daytime when they are most alert to avoid sleep during the practice. A model to use yoga nidra was developed using feedback from the school by one of the authors (KD) and was tested on patients with insomnia who volunteered.⁶

Yoga nidra unlike meditation is an aware state and is done in the supine position.⁵ The practice is easy and does not require any exercises or difficult postures, which makes it acceptable to patients with disabilities. It has been tried as a therapeutic option for some diseases,^7,8 but its role in sleep disorders is lacking. We therefore assessed yoga nidra as a therapeutic option for patients with chronic insomnia as it is safe and easy to administer.

METHODS

The study was done at a tertiary referral institute in India and was approved by the institutional ethics committee (IESC/T-394/02.11.2012). The trial was registered with the Clinical Trials Registry India (CTRI/2013/05/003682). The trial design was parallel with CBTI (recommended intervention) and yoga nidra (experimental intervention) being the two limbs. No changes were done to the methods after trial commencement. The study was conducted from 2012 to 2016.

Patients were informed about the study by placing advertisements in the institution’s campus, outpatient department (OPD) and in the city including metro stations and bus stands, and they were asked to report to the Sleep OPD at the institute. Patients diagnosed to have chronic insomnia who volunteered to be a part of the study were assessed for eligibility and randomized using the sealed opaque envelope method. All the patients were explained about the nature of the study, and informed consent was obtained. After the baseline assessment, randomization was done and the patients were referred for the intervention. The CBTI intervention was done in the sleep OPD by psychologists trained in CBTI, and the yoga nidra intervention was done by one of the investigators (KD) also in the Sleep OPD. In both groups, no drugs were stopped or changed during the study and they continued the prescribed medications throughout the intervention.

Randomization and blinding

Randomization was done using random number charts and concealment by the opaque envelop method. The assessor was blinded to the identity of the patient and also the type of intervention. The questionnaires were filled by the patient in the office at regular intervals. A unique identification number (ID) of each patient given at the time of randomization was marked on the questionnaires with date. The data were entered by the support staff who were blinded to the type of intervention for each ID. The salivary samples were collected centrally, marked with ID and date and sent for estimation. The laboratory technician was blinded to the type of intervention. The PSG files were coded, without ID and given to KD in batches of 8–10 files.

The PSG files were all scored by KD who was blinded to the patient identity and also the timing of PSG, whether baseline or post-intervention because of coding. The PSG files were decoded after scoring by another researcher and the data were entered by the staff. The sleep diary was collected from the patients at the end of the intervention and ID was marked, with personal particulars, if any, removed. These data were also filled by the staff who were blinded about the type of intervention. Figure 1 shows the study design.

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FIG 1.

The study design

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RESULTS

The intervention was implemented in both the groups as mentioned above. The recruitment announcement was done from February 2012, and the randomization after baseline assessment was started from May 2012. The trial was done with no changes in the methods after registration of the trial. The trial was continuously under the Data Safety Monitoring Board. Figure 2 shows the CONSORT 2010 flow diagram. There was no significant difference in baseline parameters of the two intervention groups (Table II).

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FIG 2.

The Consort diagram

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DISCUSSION

The CBTI and yoga nidra groups did not differ significantly in age, onset of illness or sleep parameters. We used multicomponent CBTI, which is the treatment of choice for chronic insomnia.¹⁸ Brief interventions did not show durable effects;¹⁹ hence, we had six sessions²⁰ including assessment by the therapist. Although both interventions were offered at no extra cost, a relatively large number of patients refused non-pharmacological approach because it required repeated reporting.

In the CBTI group, we did not find any difference between subjective and objective sleep parameters, though such a difference has been noted in other studies,²¹ and small effect on subjective TST with large ES in subjective SOL, WASO and SE²² has also been reported. In the same group, we found a significant increase in REM SOL with significant improvement in ISI and in depression scale though this was not significant. REM sleep duration when analysed as a percentage of TST was not significantly reduced, implying that the sleep time percentages were not significantly different from pre-treatment values. The TWD, N1, N2 and N3 calculated from PSG did not show any significant change in our study with the CBTI intervention. Several factors may be responsible for this difference. In a randomized trial by Sivertsen et al.,²³ on patients with insomnia above 55 years of age, CBTI showed improvement of SE and slow wave sleep (SWS) objectively by PSG. However, in our patients, the average age was much younger. They also had a baseline SE of >81% on PSG in all pre-treatment patients, whereas in our study, the average SE at baseline PSG was much lower (74%). We did not include a mood enhancement module which was used in a trial comparing CBTI with mindfulness meditation²⁴ as it is not a standard CBTI regimen. Studies have reported improvement in objective criteria using PSG,²² which was also seen in our study. Studies have relied on sleep diary for effective monitoring during interventions; however, actigraphy could have been used.²⁵

We found a subjective improvement in severity of insomnia and quality of sleep. Furthermore, significant reduction was seen in pre-sleep arousal. This was also found in night time arousal by Espie et al.²⁶ where online CBT was administered. A significant improvement in the stress component was seen using the DASS scale. In a study done by Okajima et al. in 2011, a correlation of the Dysfunctional beliefs and attitudes about sleep (DBAS) score with Athens Insomnia score was found at baseline, but after intervention, improvement in the DBAS score did not necessarily show improvement in the insomnia score, implying different mediators for improvement in insomnia.^21,27 We have not used improvement in the DBAS score in our study as an outcome measure for insomnia. Although initial improvement is seen with behavioural remedies,¹⁸ in our patients, the effect continued implying the effect of multi-component therapy.

In the yoga nidra group, moderate effect was seen on TST, SE and sleep quality using a sleep diary. Sleep diary analysis showed significant improvement in SE, sleep quality, wake duration and WASO. Questionnaire analysis showed significant improvement in sleep quality and in severity of insomnia. PSG showed an objective improvement in WASO. The improvement of SWS as a percentage of TST showed a moderate effect. As a percentage of TIB, SWS showed a moderate effect in PSG parameters. Yoga nidra has been found to be associated with a shift towards parasympathetic dominance,²⁸ and high cardiac vagal control is related to better subjective and objective sleep quality.²⁹ Yoga practice in the morning has been found to increase parasympathetic drive at night,³⁰ causing sleep to be more restorative. In addition, the probable mechanisms which might affect sleep quality and subjectively feeling better may be linked to cognitive structuring effects of these practices, which make the mental processing of external inputs more relaxed.³¹ Objective improvement in SWS following the yoga nidra intervention may also explain the subjective sleep quality. Mindfulness meditation is known to target deficits in executive attention which characterize mood and anxiety³² and psychological symptoms.³³ Therapies using a non-pharmacological approach are known and mindfulness meditation has been used as an approach to patients with insomnia.^34,35 Reduction in sympathetic arousal and reduced emotional states are the probable reasons for improvement in patients with insomnia with mindfulness meditation.^4,36,37

In our patients, yoga nidra produced increased TST unlike a study on meditators where a reduced sleep need due to meditation was proposed.³⁸ This brings out the difference in meditators undergoing this practice from patients where it is being used as an intervention. It is also important that the intervention be given under supervision of a sleep practitioner because the changes seen in the patients need to be assessed and monitored especially when there is an increased association with anxiety, other somatic complaints such as headaches, nausea are likely to be more in patients with insomnia,³⁹ with mind–body therapies including meditation.⁴⁰ Our guidelines for observers (Appendix A; available at www.nmji.in) are to ensure a standardized intervention along with constant supervision by sleep practitioners.

This also highlights the differences between patients and healthy controls and hence the medical supervision of these patients is important unlike a healthy person undergoing a yoga nidra intervention.

We found that yoga nidra practice showed a significant improvement in TST, SE, SOL, WASO and SWS, whereas CBTI was found to affect WASO to a large extent with mild effects on TIB, TST and SE. This suggests that yoga nidra practice may be a better treatment for sleep initiation or sleep maintenance both compared to CBTI which showed good results on WASO, but probably will not be able to reduce sleep onset. CBTI is a recommended method, but lack of therapists trained in CBTI often poses problems in implementing this intervention. Yoga nidra practice is a good adjunct therapy for patients with insomnia provided the therapy is administered under the supervision of a sleep physician with monitoring of sleep and somatic symptoms during the intervention. It is simple to perform as after a few initial sessions, the individual can be left on his/her own to perform the practice with intermittent follow-up, if required.

This practice may also be of value where the patient is in remote areas and a therapist is difficult to reach for CBTI, but once trained in yoga nidra, the patient can perform the practice on his/her own. Future research of its use in military, isolated work areas of confinement and field may further highlight its role in such operational environments.

Conclusions

We found that yoga nidra practice and CBTI improved TST and total wake duration both subjectively and objectively. The yoga nidra intervention also improved SWS and SOL in patients. Yoga nidra practice in patients with chronic insomnia should be done using formulated guidelines during sessions to monitor the patients. Discussion after the session should be done to help the patient understand the practice. Yoga nidra practice is a good adjunct therapy to improve sleep in patients with insomnia.