Freight trains , nocturnal vibration and noise , and their physiological effects during sleep

There has been much previous research examining the effects of environmental noise on sleep, but the specific influence of vibration exposure has largely been neglected and primarily limited to cross-sectional field studies. Within the EU CargoVibes project, we experimentally investigated physiological reactions to freight train vibration and noise exposure during sleep. Polysomnography was used to determine the impact on sleep architecture, in terms of macrostructure and for eventrelated autonomic and cortical arousals. The work aimed to examine the effects on sleep of vibration amplitude, number of events, and the interaction of vibration and noise. Nights with 36 events and high vibration were found to result in greatest sleep fragmentation, more changes to lighter sleep stage, shorter continuous time in slow wave sleep and earlier awakenings than the control, and increased wakefulness and reduced rapid eye movement sleep relative to the 20 train night. The likelihood of the occurrence of event-related awakenings, arousals and changes in sleep depth all increased with vibration amplitude. Heart rate response was greater during exposure to high than moderate vibration. Comparison between first and second half of the night indicated that cardiac reactions sensitized to repeated vibration exposure. Vibration in residential environments from railway freight contributes towards sleep fragmentation which may have implications for health outcomes. Guidelines to prevent adverse health outcomes for freight lines where there is a risk for vibration exposure therefore need to consider not only noise but also the added impact of vibration.