As Shaffer and Ginsberg (2017) put it, “a healthy heart is not a metronome” (Abstract). The time between beats shifts slightly from one beat to the next, and that variation is called heart rate variability, or HRV. Those small shifts let the cardiovascular system adjust quickly to physical and psychological challenges, and HRV can be measured over periods ranging from about two minutes to a full day (Shaffer & Ginsberg, 2017).
How we use it
HRV is widely used to observe how the body is shifting between effort and rest, which makes it a natural companion to biofeedback. It is also the kind of measure we would need before saying anything about what a space does to the body.
That is not hypothetical. In a five-day trial with university students, the same relaxation program delivered in immersive virtual reality produced larger favorable shifts in HRV and a greater drop in perceived stress than the program on a screen (Cohen’s d = 0.78 for the difference in perceived stress). The authors note the short intervention period and the lack of follow-up, and the trial tested virtual reality rather than physical installations (Nowakowska et al., 2026).
References
Nowakowska, A., Nowak, M., Bigas, J., Gaweł, Z., Nęcki, M., & Rutkowski, S. (2026). Short-term psychophysiological effects of immersive versus non-immersive relaxation in university students: A randomized controlled trial. Healthcare, 14(15), Article 2322. https://doi.org/10.3390/healthcare14152322
Shaffer, F., & Ginsberg, J. P. (2017). An overview of heart rate variability metrics and norms. Frontiers in Public Health, 5, Article 258. https://doi.org/10.3389/fpubh.2017.00258