Table 1.

A summary of clinical studies related to yoga nidra

Serial no.	References	Study population	Study design	Type of intervention; target condition	Duration	Results (p value)	Study findings/significance
1	Sethi et al. (1981) [25]	N = 16; patients with tension headaches; Age range16-45 years; Residents of Lucknow, India	Randomized Controlled Trial	Comparing the effectiveness of EMG biofeedback and Shavasana (yoga) asana in relieving tension headaches	3 months	Not provided	Shavasana (corpse pose) was found to be equivalent to EMG biofeedback. EMG biofeedback was effective in relieving headaches in 50% of cases, while Shavasana was effective in 43%. The further trial demonstrated a better response rate (83%) in the younger group (16–25 years) for both methods
2	Kumar (2006) [41]	N = 110; Age range 20–30 years; 80 students (M = 40; F = 40) participated in the trial, while 30 age and sex-matched controls	Controlled before-after design	Determining the efficacy of yoga nidra on Alpha EEG and G.S.R. level of the subjects	6 months	Significant improvement was observed both in alpha EEG and GSR values(P < 0.01) in the experimental group	Yoga nidra Improves alertness in both male and female students
3	Kumar and Pandya (2012) [33]	N = 110, 80 (M = 40; F = 40) DSVV students aged between 20–30 were in the experimental group and 30 (M = 15; F = 15) of similar ages served as control subjects	Controlled before-after design	The study aimed to determine the effect of yoga nidra on the erythrocyte sedimentation rate (ESR) in healthy subjects	6 months	Both male and female study subjects showed significant reductions in measured ESR rates when before-after comparisons were made (males t = 5.06, females t = 2.82)	The experimental findings demonstrate that yoga nidra can be of benefit even to supposedly healthy subjects and thus may be a useful practice for promoting optimal health
4	Kumar, (2008) [20]	N = 110, 80 (M = 40; F = 40) from PG classes of Dev Sanskriti University, aged 20–30 years. 30 age and sex-matched control subjects	Controlled before-after design	The study sought to determine the effect of yoga plus yoga nidra practice on the overall stress and anxiety levels of the study subjects as measured by the Hamilton Depression Rating Scale and the Hamilton Anxiety Rating Scale	6 months	Following 6-month of yoga nidra practice both stress (P < 2.5) and anxiety (P < 2.48) were reduced	These findings show that the addition of yoga nidra to the practice regimen of yoga students may provide incrementally greater stress reduction, although further research is needed to quantify the amount of this benefit
5	Manik et al. (2017) [42]	N = 172 participants with lumbar Spondylitis Age range = 21–79 years; from the outpatient department (OPD) of Neurosurgery, AIIMS, Bhubaneswar	Uncontrolled randomized prospective(longitudinal) study	Participants practice yoga (including nidra yoga) for one hour a day The study intended to find out the relationship between the duration of yoga (including nidra yoga) and symptomatic improvement in lumbar spondylitis	IRPG- had just one session of yoga [1], STPG group practiced for 15 days, while LTPG for one month	In I.R.P.G, P < 0.001. Moreover, the pre-score of pain was 15.203, and the post-score was 11.737. In S.T.P.H, the P-value is lesser than 0.01, and in L.T.P.G, P < 0.001.The LTPG group showed a better result than the STPG group and IRPG (P < 0.01)	Pain relief in lumbar spondylitis was directly related to the duration of practice of yoga, with the highest score and benefit in LTPG IRPG pain-score improvement of 3.333 ± 2.967 in 22.8% of participants, STPG had a pain improvement score of 7.308 ± 1.995 in 51.35%. While LTPG had an improvement of 10.00 ± 1.915 in 64.02% of cases
6	Sethi and Singh, (2016) [25]	40 Athletes (wrestlers); Age range = 18–25 years	Controlled before and after design	The goal of the study was to demonstrate the effect of yoga nidra on the anticipation time and reaction time of athletes	45 days	Subjects in the experimental group demonstrated significant improvement in reaction time (P < 0.05)	Yoga nidra improved the performance and reaction time of the athletes (wrestlers) Simple visual reaction time (t = 5.42) and Choice visual reaction time (t = 3.14) were found to be significant Anticipation time did not show any statistically relevant improvement in both groups
7	Kumar (2005) [32]	N = 40; people suffering from mild hypertension (M = 30; F = 10); Age range = 30–60 years; Where men belonged to various professions, females were predominantly housewives, the trial was carried out at Patliputra Seva Sansthan, Patna City, Patna	Uncontrolled before and after design	The practice of 30 min of nidra yoga or 15 days continually. The study sought to determine the effect of nidra yoga on hypertension (both systolic and diastolic) and emotional well-being	15 days	Significant differences were found in most of the dependent measures: Blood pressure (systolic [t = 10.13] and diastolic [t = 8.09]) readings, pulse rate (t = 6.47), and respiration rate (t = 5.02), as well as psychometric measures of stress (t = 8.12), anger (t = 4.76) and fear (t = 3.57) were all statistically significant. However, psychological depression was not significant	Yoga nidra practice can significantly reduce both physiological and psychological responses to stress It is particularly effective in controlling hypertension
8	Monika et al. (2012) [35]	150 Females with menstrual irregularities referred from the Department of Obstetrics and Gynecology CSMMU, UP, Lucknow Randomized into two equal groups of 75 each	Random controlled trial	Subjects in the experimental group took prescribed medications and practiced nidra yoga for 35–40 min a day for five days a week, while the control group took medications but did not practice yoga nidra	5 days/week for 6 months	The two groups were compared using a one-way ANOVA test. Results were significant at P < 0.05	Yoga nidra was effective in improving symptoms of menstrual irregularities (small but relevant improvement), especially in pathological amenorrhea (q-static < 1.2). Yoga nidra practice can be of benefit for improving autonomic dysfunction, heart rate, postural hypertension, sustained handgrip test, expiration-inspiration ratio, 30:15 beat ratio, Valsalva ratio, and cardiac output
9	Rani et al. (2013) [22]	N = 50 undergraduate first-year nursing students, M. M. College of Nursing, Mullana, Ambala	Uncontrolled before and after design	Instruction based 19-day course of nidra yoga, with stress levels assessed on day one and day 20th, data were collected by using a modified stress assessment scale	19 days, with each session lasting 48 min	Self-reported stress of student nurses (measured via a modified stress assessment scale) showed a significant (P < 0.05) reduction in a before-after comparison (28.2 before; 17.8 after)	Yoga nidra is an effective practice for reducing stresses associated with demanding professions such as nursing
10	Amita et al. (2009) [38]	N = 41 middle-aged diabetic patients	Controlled before and after design	20 subjects were on hypoglycemic drugs and yoga nidra, while a control group of 21 individuals was on only hypoglycemic drugs The trial aimed to find the effect of yoga nidra on blood glucose levels in diabetics, and the effect of yoga nidra on symptoms of diabetes (complication reduction)	Patients practiced yoga nidra for 30 min daily for 90 days	Blood glucose levels were significantly reduced (p ≤ 0.004)in before-after comparisons	Yoga nidra has pronounced beneficial effects on a medical condition that is generally resistant to change through conventional medical therapies After three months of therapy and yoga nidra there was an average decline of 21.3 mg/dl fasting glucose level in the experimental group, and significant reductions in symptoms such as headaches, palpitation, insomnia, sweating, anxiety, and emotional distress
11	Datta et al. (2017) [13]	2 Patients suffering from insomnia, one on medication and the other without medication	Case Reports and Series	Yoga nidra was prescribed to evaluate its role in the management of insomnia. I patient 60 years old was without any sleep-related medications, while another 78-year-old patient was taking sleep medicine Sleep diary parameters were analyzed using the Friedman test and the Wilcoxon Signed Ranks test	6 months	Not provided	Yoga nidra significantly improved the symptoms of insomnia (sleep initiation, sleep duration, sleep quality) and decreased the sleep-related symptoms of emotional distress
12	Markil et al. (2012) [36]	N = 20; M = 5; F = 15) Age range = 18–47 years	Randomized crossover study	Participants were divided into two groups randomly. One practiced hatha yoga followed by 30 min of nidra yoga, while the second group practiced only nidra yoga. The intervention aimed to check HRV (heart rate variance) after stress or without stress	A single session of hatha yoga followed by 30 min of yoga nidra, or 30 min yoga nidra alone	Both the groups demonstrated favorable changes in HRV indices. (p < 0.001)	The trial demonstrated the beneficial effect of yoga nidra on HRV (stability of the autonomic nervous system) whether performed alone or after a session of hatha yoga (or other physical activity). Yoga nidra practice tended to favorably shift the autonomic balance to the parasympathetic branch
13	Gulia and Sreedharan (2021) [39]	Post-menopausal subject	Longitudinal Case Study During COVID-19 Lockdown	Use of yoga nidra practice and exercise module. The study used 24 h actigraphy and a sleep diary	24 weeks of yoga nidra practice and exercise module (Baseline = 4 weeks)	A big boost in mood upon immediate awakening, and throughout the day. The mood shifted to a more upbeat tone. SOL reduced after four weeks, but overall sleep time improved only after 16 weeks of dual treatment. The BMI was reduced from 30.3 to 28.4 from a starting point of 30.3. Morning rising routines remained unchanged, but neither pain nor headache were noted	Yoga nidra is simple to practice at home, making it a viable non-pharmacological technique for enhancing the well-being of the elderly
14	Datta et al. (2021) [40]	41 Participants with chronic insomnia	Randomized parallel-design study	Intervention of CBTi (n = 20) or yoga nidra (n = 21). Outcome measures include both subjective (use of sleep diary) and objective measures (PSG & measurement of cortisol)	The study was conducted between 2012–2016	Salivary cortisol reduced statistically significantly after yoga nidra (p = 0.041)	Yoga nidra practice resulted in improvements in Stage N3 sleep, overall wake duration, and subjective sleep quality. After supervised practice sessions, yoga nidra practice can be utilized to treat persistent insomnia
15	Rani et al. (2011) [43]	150 Patients (75 practiced yoga nidra, while 75 were in the control group) were recruited from the Department of Obstetrics and Gynecology, C.S.M. Medical University (KGMU), Lucknow, Uttar Pradesh, India	Randomized controlled trial	To assess the effectiveness of yoga nidra therapy on the emotional well-being of women suffering from menstrual irregularities and related distress A psychometric test “Psychological general well-being” was used for all the subjects to assess the condition	6 months	Significant improvements in psychological problems related to menstrual abnormalities Decreases in anxiety (P < 0.003) and depression (P < 0.01) was found Improvements in Positive well-being general health (P < 0.02) and Vitality (P < 0.01) were also found	Statistically significant improvements were demonstrated in psychological well-being following the practice of yoga nidra
16	Rani et al. (2011) [44]	150 Patients (75 practiced yoga nidra, while 75 were in the control group) were recruited from the Department of Obstetrics and Gynecology, C.S.M. Medical University (Erstwhile KGMU), Lucknow, Uttar Pradesh, India	Randomized controlled trial	Yoga nidra therapy in patients with menstrual disorders with somatoform symptoms	6 months	Significant improvements were found in pain symptoms (P < .0.006) Gastrointestinal symptoms (P < 0.04) Cardiovascular symptoms (P < 0.02) Urogenital symptoms (P < 0.005)	Yoga nidra was found to be an effective addition to the medical treatment of somatoform symptoms in women living with menstrual irregularities over an extended period
17	Rani et al. (2013) [27]	Females of reproductive age group (18–45 years) 65 cases, 61 controls from KG Medical University, Lucknow suffering from menstrual problems	Randomized controlled trial	Individuals were randomly assigned to two groups: conventional medical treatment plus yoga nidra or conventional medical treatment only	6 months	Significant improvement in hormonal levels TSH + (P < 0.02) FSH,(P < 0.01) LH,(P < 0.001) Prolactin,(P < 0.03)	The study demonstrated the efficacy of yoga nidra on hormone profiles in patients with menstrual irregularities Yoga nidra practice was helpful in patients with hormone imbalances such as dysmenorrhea, oligomenorrhea, menorrhagia, metrorrhagia, and hypomenorrhea
18	Rani et al. (2016) [45]	100 Women with menstrual problem, residents of Lucknow. (50 received medications only, while 50 prescribed yoga nidra as adjuvant therapy along with medications)	Randomized controlled trial	The trial was intended to assess the beneficial effect of yoga nidra on the emotional well-being and hormonal balance of women with menstrual irregularities Psycho-biological General Well-Being Index (PGWBI) and hormonal profiles were assessed at the baseline and end of the study	6 months	Significant improvements were found in scores related to anxiety (P < 0.01), depression (P < 0.02), positive well-being (P < 0.01), and general health (P < 0.04)	Yoga nidra can be a successful therapy to overcome the psychiatric morbidity associated with menstrual irregularities. Therefore, yogic relaxation training (yoga nidra) could be prescribed as an adjunct to conventional drug therapy for menstrual dysfunction Yoga nidra was highly useful in reclaiming the hormonal balance
19	Rajpoot and Singh (2014) [46]	40 Emotionally abused adolescents (M = 20; F = 20) Age range = 13–19 years) were selected from various schools and coaching centers of city Chandausi (U.P.)	Uncontrolled before and after design	Role of yoga nidra in improving mental health The emotional Abuse Test developed by PushpLata Rajpoot (2011) was used along with Mental Health Battery by Singh & Gupta (1983)	2 months	NA	Significant improvements in responses to emotional abuse were shown in before and after comparisons of scores on the Emotional Abuse Test and Mental Health Battery
20	Kisan et al. (2014) [47]	60 Subjects (Age range = 15–60 years) suffering from migraine were divided into two equal groups (experimental and control group)	Randomized controlled trial	Effectiveness of relaxation techniques (yoga and yoga nidra) in migraines The control group was provided with conventional care, while the experimental group was prescribed yoga nidra along with conventional care A headache diary and lab autonomic nervous system assessment were the primary instruments used	6 weeks	Significant improvement in headache frequency and intensity was demonstrated (P < 0.001)	Headache frequency and intensity were reduced more in yoga nidra with conventional care than the conventional care group alone. Furthermore, Yoga nidra therapy enhanced the vagal tone and decreased the sympathetic drive, hence improving the cardiac autonomic balance. Thus, yoga nidra therapy can be effectively incorporated as adjuvant therapy in migraine patients
21	Kumar (2013) [48]	110 Subjects who had been evaluated for guilt and regression () were selected from Dev Sanskriti University. 80 were included in the experiment group and 30 in the control group	Controlled before and after design	The trial intended to demonstrate the effectiveness of yoga nidra in reducing guilt and regression Both groups practiced yoga, however, the experiment group practiced yoga nidra additionally	6 months	Results were significant at P < 0.01	Yoga nidra positively decreases the level of regression and guilt in males
22	Jensen et al. (2012) [49]	10 participants, 7 living with disruptive behavior (DB) disorder and being medically treated for it, while 3 were healthy subjects (control group) Age range = 10–15 years)	Controlled before and after design	Effect of yoga nidra in improving disruptive behavior in youth and breathing pattern (regularity, change of dominance of thoracic to abdomen) Respiratory Inductive Plethysmography (RIP) was used to assess the pattern of breathing	13 week	NA	Result showed more stable breathing during yoga nidra compared with pre- or post-recording periods. Also seen were reductions in thoracic dominance during the practice and reduced anxiety, hyperactivity, emotional liability, and inattentiveness in the experimental group after yoga nidra
23	Anderson et al. (2017) [50]	N = 9; registered nurses working at inpatient urban psychiatric clinic Age range = 24–49 years	Uncontrolled before and after design	A study of the effect of yoga nidra in reducing stress-related to psychiatric nursing practice A Likert scale was used to assess stress levels pre and post-intervention One and a half hours of six yoga nidra training sessions were provided to the participants	4 week	NA	One self-report measure showed significant benefits from yoga nidra. Muscle tension and perceived stress level were greatly reduced