In-vehicle multi-sensory experiences can reduce mental stress.

Daily stress is a widespread and growing concern that impacts both mental and physical well-being. Although many evidence-based strategies exist, including yoga, mindfulness, cognitive-behavioral techniques, and sensory approaches such as scent, massage, auditory, and visual stimulation, they often require time, training, or specialized environments, which limits their accessibility in everyday life. This study explores an alternative, practical approach by evaluating a multi-sensory in-vehicle relaxation system designed for use while the vehicle is stationary. Given that personal vehicles are central to daily routines, they present an underutilized yet promising space for passive stress recovery. Forty-eight participants engaged in three conditions following a stress-inducing cognitive task: a control (no relaxation), multi-sensory relaxation without scent, and multi-sensory relaxation with scent. Physiological responses were measured via EEG and ECG, and subjective stress ratings were collected to assess each condition's impact. Both multi-sensory relaxation experiences (with and without scent) significantly reduced stress compared to the control. The relaxation methods resulted in a 33 ms increase in mean RR, a 5 ms increase in RMSSD, and an increase in the alpha/beta ratio at frontal EEG channels. Ninety-eight percent of participants preferred the relaxation experience over the control experience, and 62 % indicated they would use it regularly in similar scenarios. These findings suggest that multi-sensory relaxation methods can reduce stress following a cognitively demanding task and are well-received by participants. Integrating such relaxation experiences into vehicles could reduce stress.