Vinyasa yoga (VY), a form of yoga that links breath with movement and has higher energy expenditure perhaps than most other types of yoga, has been sparsely studied for its effects on sleep among adults with insomnia. It remains unknown whether and how an acute bout of VY performed in the evening impacts sleep and autonomic function. The purpose of this study it to examine the effects of an acute session of VY performed in the evening on sleep and nocturnal heart rate variability (HRV) in adults with insomnia symptoms.
33 insufficiently active adults (84.8% female; 78.8% White; age=34.9±10.6 y; body mass index=28.9 kg/m2) with at least mild insomnia symptoms (Insomnia Severity Index ≥ 10) were randomized to either a single 60-min session of VY (n=17) or a quiet rest control condition (CON: n=16) occurring between 15:00 and 20:00 h. VY followed a pre-recorded practice and CON watched a nature documentary. On one night before and after the experimental session, participants wore a wrist accelerometer and a chest heart rate (HR) monitor overnight and completed a sleep diary. HRV was derived from the entire HR recording across the nocturnal period and standardized for sleep duration, with root mean square of successive differences (RMSSD) as the primary outcome. Analyses compared the changes from pre- to post-session between groups using linear mixed models and Cohen’s d effect sizes.
The change in actigraphy-assessed sleep efficiency (SE) and total sleep time (TST) did not differ from pre- to post-session for VY (SE: 88.9±1.4 to 88.9±1.5%; TST: 454.7±15.8 to 445.8±17.4 min) or CON (SE: 89.4±1.4 to 88.7±1.6%; TST: 401.3±16.3 vs. 407.3±17.3 min); group x time interactions were not statistically significant (each p > 0.48). The change in nocturnal RMSSD did not differ from pre- to post-session for either VY (39.5±6.8 to 38.7±6.0 ms) or CON (37.6±7.0 to 35.8±6.2 ms) and the group x time interaction was not statistically significant (p=0.94).
An acute bout of VY performed in the early evening did not significantly change accelerometer- or diary-assessed sleep or impact parasympathetic tone during sleep. VY in the early evening is unlikely to benefit or impair sleep in adults with insomnia symptoms.