Vestibular habituation is associated with distinct autonomic signatures and greater reduction in visually induced motion sickness: A randomized controlled trial.

This study compared the efficacy of short-duration, high-intensity versus stepwise, progressively lengthened optokinetic drum-chair training in alleviating visually induced motion sickness (VIMS) and modulating autonomic function. Ninety-six VIMS-susceptible university students were randomly assigned to either a short-duration (S-D) group (one training session daily for 3 consecutive days, with each session terminated upon the first report of pronounced nausea) or a stepwise (S-W) group underwent a 6-day graduated protocol (one session daily, duration: 60 s/120 s/180 s). Efficacy was assessed by comparing pre- and post-intervention 90-second chair-rotation challenges. The primary outcome was the Graybiel motion-sickness score (Graybiel score); secondary outcomes included frequency-domain heart rate variability (FD-HRV), electrodermal activity (EDA), and skin temperature (SKT). The S-W group showed a greater reduction in Graybiel scores than the S-D group (median change: -9.0 versus -5.0; between-group Hodges-Lehmann difference: -3.0 points; 95% CI -7.0 to -1.0). Autonomically, the S-W group reduced both low-frequency (LF) and high-frequency (HF) power and increased the LF/HF ratio, while The S-D group reduced only HF power. Skin conductance response amplitude (SCR) increased in the S-W group only. SKT decreased substantially (2-4 °C) in the S-D group but minimally (< 1 °C) in the S-W group (between-group P < 0.01, baseline-adjusted). In conclusion, the stepwise protocol was associated with greater VIMS symptom relief and a more favorable autonomic profile than the short-duration approach, suggesting it may serve as a potential non-pharmacological countermeasure for virtual reality or simulator settings.