Background

    Rather than a sleep disorder, insomnia may be a disorder of inappropriate arousal.[1] Since yoga can reduce psychophysiological arousal,[2] could it alleviate insomnia?

    The study

    In this 8-week randomized controlled trial, 40 people aged 25–59 with primary sleep-onset insomnia (meaning the problem wasn’t waking up in the middle of the night but falling asleep in the first place, and it had no known cause) were randomized to either 45 minutes of Kundalini yoga daily (with a special focus on breathwork) or a sleep-hygiene treatment (SH) just before bedtime.

    The SH group received these instructions:

    • Restrict caffeine consumption to three cups of coffee per day and cease intake by late afternoon.
    • Limit alcohol intake.
    • Engage in regular moderate exercise several times a week, particularly in the late afternoon or early evening.
    • Consume a light bedtime snack (cheese, milk, and peanut butter were provided as examples of appropriate foods).
    • Minimize light and disruptive noise in the bedroom (use earplugs, a white-noise machine, dark shades over the windows …).
    • Keep the bedroom temperature comfortable.

    The primary outcome was the average sleep onset latency (SOL: the time it takes to fall asleep) at 8 weeks, as measured by daily sleep diaries.

    The secondary outcomes were total sleep time (TST), number of nocturnal awakenings, total wake time (TWT), wake after sleep onset (WASO), sleep quality, sleep efficiency (SE: the ratio of total sleep time to time in bed), restedness as measured by daily sleep diaries, as well as changes in sleep measured by the Pittsburgh Sleep Quality Index (PSQI), the 7-item Insomnia Severity Index (ISI), the 9-item Self-Efficacy for Sleep Scale (SES), the 13-item Insomnia Symptom Questionnaire (ISQ), and the somatic and cognitive subscales of the Pre-Sleep Arousal Scale (PSAS).

    Each outcome was measured at baseline, after the 8-week intervention, and 6 months later.

    The results

    Compared to baseline, yoga improved SOL, SE, TST, and TWT, as well as ISQ, PSQI, and SES scores. Compared to SH, yoga led to better TST as well as ISQ and SES scores. For SOL, SE, TST, TWT, ISQ, and SES, these results were still valid 6 months after the intervention.

    Remission was defined as less than 30 minutes for SOL and more than 80% for SE. Compared to SH, yoga led to higher rates of remission based on both SOL (65.0% vs. 36.8%) and SE (80.0% vs. 47.4%). It retained its advantage at 6 months for both SOL (82.4% vs. 36.4%) and SE (88.2% vs. 54.5%).

    Note

    This trial had two specific strengths: it adjusted for multiple comparisons for primary and secondary outcomes, which decreases the risk of false positives, and it was preregistered with a prespecified primary outcome. However, secondary outcomes were not prespecified, and the trial ended up having a lot of them. Other limitations include a relatively small sample size, a narrow population (i.e., mostly White women), and too much reliance on subjective measures.

    This Study Summary was published on June 4, 2021.

    References

    1. ^David A Kalmbach, Daniel J Buysse, Philip Cheng, Thomas Roth, Alexander Yang, Christopher L DrakeNocturnal cognitive arousal is associated with objective sleep disturbance and indicators of physiologic hyperarousal in good sleepers and individuals with insomnia disorderSleep Med.(2020 Jul)
    2. ^Elisabeth Mocanu, Christine Mohr, Niloufar Pouyan, Simon Thuillard, Elise S Dan-GlauserReasons, Years and Frequency of Yoga Practice: Effect on Emotion Response ReactivityFront Hum Neurosci.(2018 Jul 4)