Chronic insomnia is a common sleep problem and is associated with increased morbidity and mortality (Taylor et al. 2007). Available treatment options include pharmacological and non-pharmacological approach. Studies have shown sleeping pill users at a greater mortality risk (Kripke et al. 2002) and though drugs like zolpidem have been found to be safe for short term use (Schutte-Rodin et al. 2008) but when taken for years these medications also produce unwanted side effects like sleep related eating disorders and sleep walking (Hoque and Chesson 2009) and even increased cancer risk (Kao et al. 2012).

Non pharmacological approach using cognitive behavioral therapy for insomnia (CBTI) is considered beneficial. CBTI though remains the first line of therapy for insomnia but is often underutilized (Schutte-Rodin et al. 2008). Underutilisation of CBTI is reported because of reasons which are both patient centred and system based issues. Patient related reasons include time and cost involvement and limited availability of CBTI trained specialists being a major system based problem.

Complementary and alternative medicine in the form of Kundalini yoga (Khalsa 2004), Tai Chih Chi (Irwin et al. 2008), mindfulness meditation (Ong et al. 2014), acupuncture and Chinese herbal medicines have been tried in insomnia patients. There is a felt need to complement the existing gamut of treatment options for insomnia patients.

According to the ancient Indian scriptures, sages are known to sleep using yoga nidra. Yoga Nidra is derived from two Sanskrit words, ‘Yoga’ (‘yuj’ = yoke) meaning union or one pointed awareness and ‘nidra’ means sleep. Yoga nidra is derived from ‘pratyahara’ of raja yoga and tantric practise of ‘nyasa’. In ‘pratyahara’ mind and mental awareness are dissociated from the sensory channels. ‘Nyasa’ means ‘to place or to take the mind to that point’. Yoga nidra is documented as neither nyasa nor meditation as yoga nidra is done in supine position and unlike meditation which is an aware awake state, yoga nidra is considered as aware sleep state (Saraswati 1998). ‘Nyasa’ is practised in sitting posture and involves the recitation of mantras in Sanskrit to experience different parts of the body which increases the scope of this practise beyond different cultures.

Yoga nidra was known to be practised by sages and it was passed on to their disciples traditionally. Swami Satyananda Saraswati, renowned teacher from Bihar School of Yoga, Munger, Bihar, India laid down the basics of learning yoga nidra in the form of a book. He described yoga nidra as a ‘systematic method of inducing complete physical, mental and emotional relaxation and in this state the relaxation is achieved by turning inwards, away from outer experiences’ (Saraswati 1998). It can be done following instructions from his book by a teacher or by a way of audio compact disc (CD).

Yoga nidra has been tried as a therapeutic option for many diseases. The relative ease of practise has made it an acceptable therapeutic option for many diseases. Yoga nidra has been used in patients of menstrual abnormalities (Rani et al. 2011), post- traumatic stress disorder (Stankovic 2011), diabetes (Amita et al. 2009), anxiety and depression (Rani et al. 2012) but little is known about its effect on sleep or sleep disorders.

Although we find description of yoga nidra in literature, there is no scientific report of its application in sleep disorders.

Since yoga nidra has been used as a therapeutic option with no documented side effects and it is mentioned related to sleep in scriptures, there was a felt need to develop this method as a model in management of chronic insomnia patients.

The objective of the study was to develop yoga nidra as a complementary model in management of chronic insomnia patients. Authors had asked for volunteers through advertisement placed at various OPDs. Two patients aged 60 and 78 years, who volunteered for the model of yoga nidra, are discussed. They were explained about the nature of study and informed consent was obtained. The study was approved by the Institutional ethical committee of All India Institute of Medical Sciences, New Delhi, India (reference number IESC/T-394/02.11.2012).

Diagnosed chronic insomnia patients came from sleep clinic out patients department (OPD) of MT¹, senior neurologist and certified sleep specialist. They were on treatment and were referred to KD² in case they volunteered to add yoga nidra intervention to the already prescribed treatment. An informed consent from the patient was taken.

Two patients Patient 01 and 02 underwent the intervention using yoga nidra model.

Patient 01: 60 years old widower with complaints of not able to sleep after getting up at night since 20 years for more than 30 min and more than three times a week. Patient had worry at daytime regarding falling off to sleep which became even worse at bedtime. Patient had history of benign prostatic hypertrophy and had no history of any medications for sleep or any other disease.

Patient 02: 78 years old male self-employed, company owner with complaints of not able to sleep after getting awake at night for more than 30 min and more than three times a week since 15 years. He felt quite energetic during the day due to the work requirement but in the evening started feeling anxious about sleep problem which worsened at bedtime. He was on tablet clonazepam 0.25 mg HS off and on since 1 year.

KD² visited Bihar School of Yoga, Munger and attended sessions of yoga nidra taken by teachers. Permission to use yoga nidra for chronic insomnia patients was taken. She had discussions with the teachers and doctor in the school. The teachers brought out the usual problems faced during conducting and also while doing the session oneself. KD² also did sessions herself under supervision while in ashram to get a hands-on feel of the session which would help planning for the patients subsequently. Planning of the session was done keeping the discussion in mind. The patients were taught using pre-recorded audio CD on yoga nidra© from the school which are easily available for sale.

The discussion brought out that a yoga nidra session every day for 3 to 4 days as done in short yoga programmes helps their subject to make them comfortable during the session. It was also pointed out that at times the instructions are not clear to all the subjects and might require elaboration on an individual basis. Keeping these points in mind five supervised sessions were planned continuously every day for 5 days. The method of doing yoga nidra involves seven steps namely – preparation, samkalpa (samkalpa = idea or notion formed in the heart or mind), body part awareness or rotation of consciousness, breath awareness, feeling and sensation, visualization and ending of practice (Saraswati 1998).

What to do during the session for the observer

The patient was not interrupted during the session. Signs of restlessness e.g. tossing and turning, moving hands, shutting eyes too tightly, not looking relaxed etc. were observed. Cues of whether the patient was following instructions were carefully noted e.g. When the instructor asked the subject to take a deep breath, or look down while keeping eyes closed, the observer made a note of whether the patient followed. In case the patient was found not following instructions or appeared restless, time of the practise was noted from the player and subsequently discussed after the session.

Yoga nidra intervention was done using a copyrighted pre-recorded Yoga Nidra audio CD approximately 27.2 min from Bihar School of Yoga, Munger, Bihar, India. Conduct of yoga nidra session was done in a sound proof room, with minimal ambient lighting during daytime. The subject was made to lie in the supine posture on a comfortable mattress. The entire session was done in shavasana (shava means “corpse” and asana means “posture”). The posture used for this asana is lying on the back, the arms and legs are kept at about 45° with the palms facing upwards. A soft pillow is optional to give maximum comfort to the patient while the entire session. This posture minimises the contact points especially between the limbs of the body. Brief outline of practise of doing yoga nidra and general instructions given to subjects is attached in ‘Additional file 1’ (Saraswati 1998).

Two fortnightly follow ups were considered mandatory for the patients after the start of yoga nidra intervention. During this study, patients were also instructed to meet MT¹ at least at the end of the month and at any time when the patient felt he deteriorated during this intervention.

Assessment of outcome measures

Primary outcome measures which were considered for improvement of patients were related to sleep and also improvement in daytime functioning (Edinger et al. 2015). These were sleep diary parameters -total sleep time, total wake duration, overall rating of sleep quality and Insomnia Severity Index for assessment of sleep. Day time functioning was evaluated by depression anxiety and stress scores during daytime using DASS and sleepiness during the day using “ESS © MW JOHNS 1990–1997 (Johns 1991). USED UNDER LICENSE”. Pre sleep arousal scale was also used. From this scale a total score, somatic and cognitive score of pre sleep arousal were calculated. A reduction in these scores occurs with reduction in pre sleep arousal. An increase in insomnia severity index, ESS©MW JOHNS 1990–1997 (Johns 1991) and DASS shows increase in severity in insomnia, increase in daytime sleepiness and increase in depression, anxiety and stress scores respectively.

Study design consisting of first 2 weeks of baseline followed by intervention using supervised yoga nidra training is shown in timeline in Fig. 1.

Baseline assessment

After obtaining informed consent from the patient, as a baseline assessment apart from the 2 weeks sleep diary the patients had to fill sleep questionnaires ISI, “ESS (Johns 1991) © MW JOHNS 1990–1997. USED UNDER LICENSE”, PSQI and pre sleep arousal scale. Patients also filled MES which was used to screen subjects and only those with morning preference were used for the study. Baseline PSG was done. This was done not only to assess insomnia but also to document presence of other sleep disorders.

Yoga nidra supervised sessions

Yoga nidra training was done using copyrighted CD. After 05 days of yoga nidra training under supervision, the patients were instructed to practice yoga nidra at home daily at a time when he was alert.

Assessment at the end of two weeks

PSQI, “ESS (Johns 1991) © MW JOHNS 1990–1997. USED UNDER LICENSE”, ISI, and PSAS and patient were instructed to fill sleep diary for the next 14 days.

Assessment at the end of four weeks

Questionnaires like PSQI, “ESS (Johns 1991) © MW JOHNS 1990–1997. USED UNDER LICENSE”, ISI, and PSAS were completed by the patient and 2 weeks sleep diary of the past 2 weeks was collected as assessed.

After yoga nidra intervention, we found significant changes in sleep parameters. In the first patient total sleep time did not change significantly though sleep onset latency and WASO improved significantly. In our study patients were instructed about sleep hygiene principles as a result of which excessive lying in bed was reduced. That may explain improvement in sleep onset latency in this patient. In the second patient both total sleep time and sleep onset latency showed improvement with no significant changes in WASO. Yoga nidra has been found to be associated with shift towards parasympathetic dominance (Markil et al. 2012). High cardiac vagal control is related to better subjective and objective sleep quality (Werner et al. 2015). Yoga practise in the morning has been found to increase parasympathetic drive at night (Patra and Telles 2010) causing sleep to be more restorative which may explain significant improvement in sleep quality ratings and WASO.N3% TST improved with intervention which is a reliable indicator in PSG in insomnia (Israel et al. 2012). This increase in slow wave sleep may be responsible for the improved sleep quality. 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 (Deepak 2002). Though probable mechanisms involved with yoga nidra are not clear at present but mindfulness meditation is known to target deficits in executive attention which characterise mood and anxiety (Ainsworth et al. 2013) and psychological symptoms (Smernoff et al. 2015). Reduction in sympathetic arousal and reduced emotional states are the probable reasons for improvement in insomnia patients with mindfulness meditation (Ong et al. 2014; Morin et al. 1992; Ong et al. 2008; Ong et al. 2009; Martires and Zeidler 2015).

In our patients yoga nidra did not reduce total sleep time unlike a study on meditators where a reduced sleep need due to meditation was proposed (Kaul et al. 2010). Yoga nidra has been used in diseases and has been found to reduce perceived stress and anxiety (Rani et al. 2011; Stankovic 2011; Amita et al. 2009; Rani et al. 2012). In our patient we found improvement in depression and anxiety scores at 3 months of intervention. At 2 weeks patient 02 showed increased anxiety and stress and that may be attributable to his personal commitment of a business trip and his apprehension of doing yoga nidra which became better in subsequent trips. This is important to understand while planning this model that initial support is important during initial 3 to 4 weeks of intervention. Following the yoga nidra model planned for the patients there was no adverse effect reported but it is 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 specially when an increased association to have anxiety, other somatic complaints like headaches, nausea is likely to be more in insomnia patients with mind body therapies including meditation (Jacobsen and Edinger 1982; Carlson and Nitz 1991).

This highlights the differences between patients and meditators and hence the medical supervision of these patients is extremely important.

Yoga nidra is easy to administer, relatively safe and does improve sleep in chronic insomnia. Another advantage of yoga nidra model is, that after the first five supervised sessions the patient is not dependant on the therapist, on the contrary he can do it all by himself in the comfort of his own house. This also gives confidence to the patient and alleviates his anxiety as seen in one of our patient. This may be one of the important factors for sustained improvement in anxiety and stress in both patients at 3 months of intervention.

The model developed for yoga nidra intervention can be used in chronic insomnia patients as an adjunct in management of chronic insomnia. Initial monitoring by a sleep physician should be done during 3 to 4 weeks of intervention. Though there are potential benefits of yoga nidra in insomnia patients, exact mechanism of yoga nidra is not yet clear. In our study both the volunteers were of elderly age group. Another limitation of our study is that in this case report there is a limited sample size (2 cases), so no firm conclusions can be drawn yet, until further studies are done on a larger number of patients. The efficacy of yoga nidra can be better understood in a randomised controlled trial in comparison to CBTI preferably in a younger age group.