Yoga Nidra for Insomnia and Posttraumatic Stress Symptoms

Retention will be quantified as percentage of participants that complete different levels of the acute protocol (i.e. ≤25%, 26-50%, 51-75%, > 75% of daily questionnaires, and second at-home PSG) and percentage that complete the follow-up questionnaires.

Adherence will be quantified as percentage of participants that complete 1-7 sessions in each week. Also, a measure of 'quality of meditation' (assessed using the PQ-M for each reported meditation) will serve as an additional measure of adherence.

At-home polysomnography will be used to measure sleep architecture. Sleep characteristics of interest include N3 percentage, Sleep onset latency, Wake after sleep onset time, Total sleep time, Sleep spindles, and REM theta.

This will be assessed using the Consensus Sleep Diary - E, with an additional question administered in the morning to record number of nightmares experienced. Daily sleep characteristics will include: total sleep time, sleep onset latency, wake after sleep onset time, and number of nightmares.

A daily version of the PCL-5 8-item version will be administered each day, for participants to complete shortly before going to bed. The PCL-5 8-item version is an abbreviated version of the full-length PCL-5, with 2 symptoms assessed for each symptom cluster and ratings on a 5-point Likert scale (0 = Not at all bothered, 4 = Very bothered).

The PTSD Checklist for the DSM-5 (PCL-5) is a self-report questionnaire used to assess severity of DSM-5 PTSD symptoms over the past month. It includes 20 items (5 per symptom cluster), each rated on a 5-point Likert scale (0 = Not at all bothered by, 4 = Extremely bothered by).

The Insomnia Severity Index (ISI) is a 7-item questionnaires that assesses the severity of daytime and nighttime components of insomnia over the past two weeks. A 5-point Likert scale (0 = No problem, 4 = Very severe problem) is provided for each item, and scores range from 0 to 28, with higher scores indicating greater insomnia severity.

The Five Facet Mindfulness Questionnaire, 15-item version (FFMQ-15) assesses five facets of mindfulness (Observing, Describing, Acting with Awareness, Nonjudging of Inner Experience, Nonreactivity to Inner Experience). Each item is rated from 1 to 5 ( 1 = Never or very rarely true; 5 = Very often or always true) according to what is generally true for the respondent, and there are 7 reverse-scored items. For all FFMQ-15 subscales, scores range from 3 to 15, with higher scores indicating greater mindfulness.

The Client Satisfaction Questionnaire-8 (CSQ-8) is an 8-item measure of satisfaction with a treatment. Each item is rated on a 4-point Likert scale, in which "1" indicates the lowest level of satisfaction and "4" indicates the highest level of satisfaction.

At conclusion of the daily monitoring period (Post-treatment/waitlist or Dropout), participants will respond to 10 questions intended to assess daily survey acceptability on a 7-point Likert scale (1 = Strongly Disagree; 7 = Strongly Agree) (adapted from Mintz et al., 2024).

The Brief Experiential Avoidance Questionnaire (BEAQ) is a 15-item scale, abbreviated from the Multidimensional Experiential Avoidance Questionnaire (MEAQ). There are six subscales (Behavioral Avoidance, Distress Aversion, Procrastination, Distraction/Suppression, Repression/Denial, and Distress Endurance). Each item is rated on a 6-point Likert scale (1 = Strongly disagree; 6 = Strongly agree).

The Nightmare Disorder Index (NDI) is a 5-item measure used to assess frequency, characteristics, distress, and impairment due to nightmares over the past month, according to DSM-5 criteria for nightmare disorder. Each item is assessed on a 5-point Likert scale from 0 to 4.

The Pittsburgh Sleep Quality Index (PSQI) is a 19-item questionnaire used to assess sleep quality over the past month, with higher scores indicating worse sleep quality. A score of > 5 is typically considered to indicate poor sleep.

The Emotion Regulation Questionnaire-9 (ERQ-9) is a 9-item questionnaire used to assess tendency to use two emotion regulation strategies (reappraisal and suppression). Items are rated on a 7-point Likert scale from 1 (Strongly disagree) to 7 (Strongly agree).

The Sussex-Oxford Compassion for the Self Scale (SOCS-S) is a 20-item questionnaire used to assess self-compassion. Each item is rated on a 5-point Likert scale (1 = Not at all true, 5 = Always true).

The Beck Depression Inventory-II (BDI-II) is a 21-item self-report questionnaire used to assess major depression symptoms over the past 2 weeks. Each item is rated on a Likert scale from 0 to 4, with higher scores indicating greater severity.

The State Trait Anxiety Index, Form Y-2 (STAI) is a 20-item self-report questionnaire used to assess anxiety severity. Participants are asked to rate each item on a Likert scale from 1 to 4 (1 = Not at all, 4 = Very much so) to indicate how they generally feel.

Qualitative feedback on the acceptability, content, and structure of the intervention will be obtained during semi-structured interviews, which will be conducted with yoga nidra (high dose and low dose) participants in person after the treatment period.

The number of intrusive memories and (if any) their distress and vividness, as rated on a 7-point Likert scale (1 = Not at all; 7 = Extremely), will be recorded by participants each day before going to bed.

For participants in the yoga nidra groups, Practice Quality-Mindfulness (PQ-M; Del Re et al., 2022), a 6-item questionnaire, will be used to monitor meditation practice quality daily throughout the intervention. For each statement, participants are asked to indicate the approximate percentage of time that their meditation experience reflected the statement. The PQ-M is comprised of two components: receptivity and attention.

Heart rate variability will be derived from resting-state heart rate, as measured before and after the intervention period.

Resting-state skin conductance will be measured with the Empatica EmbracePlus wristbands before and after the intervention period.