Area under the curve (AuC), number of event-related awakenings, initial and delayed maximal increase of heart rate (HR) and number of participants with an event-related change of HR of at least 3 bpm are presented for each of the four experimental nights. AuC, initial and delayed maximal increase of HR are presented for the combined low-vibration and high-vibration conditions. Cave: the initial and delayed response is calculated as maximal increase within the first 10–15 or 20–48 s after train onset. This difference in search area explains partly the differences between the initial and delayed increase of HR.