Napping is known to have many benefits for cognitive and psychological health, specifically improving alertness and mood and reducing stress. Relaxation prior to napping can enhance its effectiveness, and while auditory relaxation is commonly used, Virtual Reality (VR) offers an immersive environment that integrates visual and auditory senses, potentially producing greater relaxation effects. However, studies measuring the effects of VR-based audiovisual relaxation on napping remain limited. In our experiment, 12 participants experienced a nap with VR-based audiovisual relaxation and a nap with auditory relaxation. The results showed that napping with VR-based audiovisual relaxation significantly increased HRV scores, an objective indicator of stress, compared to napping with auditory relaxation, while no significant differences were found in alertness and mood. These findings suggest that VR-based relaxation may further enhance stress reduction during naps, warranting further research into its applications across various settings.