The study will examine the effect of Restorative Yoga self-practice on sleep disturbance in the Chinese adult population. Restorative Yoga is a relaxation-focused yoga style which includes a series of static stretching poses and mindful breathing. Existing literature has demonstrated that face-to-face yoga sessions of different types are effective in improving sleep disturbance and reducing the severity of insomnia. There were pilot studies conducted on the effect of yoga on cancer patients' sleep quality, but research that focuses on insomnia population is rare (Wang et al., 2020). In addition, there is very limited research on the effectiveness of self-practice without the presence of a yoga instructor. Given the social distancing policy under COVID-19 and the need to stay home, this study can shed light on whether self-practice at home can be an effective alternative to face-to-face yoga sessions.

This study will be a pilot randomized controlled trial on the effectiveness of restorative yoga self-practice for sleep disturbance. Prior to all study procedures, online informed consent (with phone support) will be obtained from potential participants. Around 30 eligible participants will be randomly assigned to either the yoga group (intervention group) or the waitlist control group in a ratio of 1:1. The randomization will be performed by an independent assessor using a computer-generated list of numbers. No deception is necessary.

Participants in the intervention group will receive links to two 60-min videos per week for 8 consecutive weeks. Each video will include a yoga practice guided by a certified yoga instructor. The intervention group is required to perform the yoga practice at least two times per week. If preferred, they can do additional sessions with the videos and record their total hours of self-practice. The waitlist control group will receive the video links subsequent to the 8-week study. The intervention group will complete a set of online questionnaires before the intervention commences, weekly during the intervention period, immediately after the intervention, and 4 weeks after the intervention. The waitlist control group will complete the same set of online questionnaires before the intervention commences and immediately after 8-week intervention period has ended.

Inclusion Criteria:

1. Hong Kong residents aged 18-59 years;
2. Cantonese language fluency;
3. A global Insomnia Severity Index (ISI) score of 10 or higher;
4. No yoga experience within the 6 months before the study; and
5. A willingness to provide informed consent and comply with the trial protocol.

Exclusion Criteria:

Participants were excluded if they

1. are pregnant;
2. are having unsafe conditions and are not recommended for restorative yoga by physicians;
3. have major psychiatric, medical or neurocognitive disorders that make participation infeasible or interfere with the adherence to the yoga practice;
4. have insomnia due to specific medical conditions, side effects of medication intake or other sleep disorders; and
5. are shift workers.