Estimating psychophysiological loads by repeated temperature steps on humans using a state-space model

Area of Science:

• Environmental Health
• Human Physiology
• Psychophysiology

Background:

• Humans frequently experience indoor and outdoor temperature fluctuations globally.
• The health and fatigue risks associated with these temperature differences are not well understood.

Purpose of the Study:

• To investigate the psychophysiological stress induced by repeated short-term temperature variations in Japanese individuals.
• To quantify the accumulated effects of environmental temperature steps.

Main Methods:

• Twenty-eight healthy participants were exposed to controlled temperature changes (0°C, 5°C, 10°C, and 15°C steps).
• Psychological and physiological responses, including heart rate variability (HRV) indices, were recorded.
• A Bayesian state-space model was employed to estimate accumulated effects (load) versus direct environmental effects.

Main Results:

• Repeated temperature steps led to a continuous increase in autonomic nervous system load, indicated by decreased high-frequency (HF) RRI and increased low-frequency/high-frequency (LF/HF) RRI.
• The 15°C step (T21-36) resulted in a lower autonomic load compared to the 10°C step (T26-36).

Conclusions:

• Sudden, uncontrollable environmental temperature changes impose a significant load on the autonomic nervous system.
• Findings can inform fatigue management strategies and public health recommendations to mitigate adverse health effects from environmental temperature shifts.