Abstract
Increases in ambient temperatures pose a potential risk to mental and physical health. Heat has already been associated with alterations in bodily stress systems, and stress in turn is another major risk factor for various diseases. Yet, the precise impact of moderate temperature rises on stress reactivity remains unclear. This study investigated associations between moderate room temperature variations (17°C-28 °C) and physiological (cortisol, alpha amylase, heart rate, and mean arterial pressure) and subjective stress reactivity in 73 healthy adult participants exposed to a psychosocial stressor, the Trier Social Stress Test. Higher room temperatures were associated with increased reactivity in both the hypothalamic-pituitary-adrenal axis (cortisol concentrations) and the autonomic nervous system (alpha amylase activity, heart rate, mean arterial pressure), but not subjective stress. These findings highlight a potential pathway through which rising temperatures could exacerbate stress-related health vulnerabilities, even in non-extreme conditions.