Physiological responses to short-duration noise events during sleep

This study investigates whether short-duration noise events can elicit measurable physiological responses during sleep. While the Night Noise Guidelines for Europe define awakening thresholds based on individual noise events, the cited noise duration of 42 s is much longer than typical environmental sounds outside transportation noise. In this study, 13 participants were exposed to 3-s chirp sounds at 65 and 50 dB during sleep. Changes in heart rate, respiratory rate, and body movement (Cole’s activity index) were analyzed, comparing conditions with and without noise exposure. To evaluate these effects, the differences in physiological variables before and after noise exposure were statistically compared with the corresponding average changes in non-exposure periods using a paired permutation test. At 65 dB, heart rate increase, respiratory rate, and Cole index showed significant increases. At 50 dB, significant increases were observed in heart rate increase and Cole index. These results indicate that even short-duration noise events of only 3 s at 50–65 dB can induce physiological changes during sleep. The findings emphasize the need to consider not only the sound pressure level but also the duration and type of noise in assessing sleep-related health risks.