The impact of railway vibration and noise on sleep

Abstract

Sleep is a vital component of good health, and sleep loss is associated with impaired cognition, decreased psychomotor performance, cardiovascular disease, adverse effects on endocrine and metabolic function, negative mood, impaired memory, and more. A growing burden of freight transporta-tion on global railway networks will likely lead to an increase in nocturnal vibration and noise at nearby dwellings. However, there is currently limited knowledge on how railway freight vibration and noise may disrupt sleep. Over a series of laboratory studies in young healthy adults, the effect of vi-bration and noise from railway freight was investigated. Objective sleep was recorded with polysomnography, cardiac activity was recorded with elec-trocardiography and subjective sleep quality and disturbance was recorded with questionnaires. Increased cardiac activation occurred at vibration am-plitudes only slightly above wakeful perceptual detection thresholds. Arousals, awakenings and alterations of sleep structure began to manifest at only slightly higher vibration amplitudes. With increasing vibration ampli-tude, heart rate and the probability of event-related cortical response in-creased in a dose-dependent manner, with accompanying adverse effects on perceived sleep quality and sleep disturbance. Perceived disturbance was more pronounced among noise-sensitive individuals, although no signifi-cant physiologic differences were found relative to non-sensitive counter-parts. Rather than affecting overall sleep architecture, vibration and noise interfered with the normal rhythms of sleep, although the impact of this on long-term physical and mental health is currently unclear. Cardiac response persisted with increasing number of events, indicating an absence of habit-uation. Vibration and noise were additive regarding their effect on cortical arousal and sleep stage change, demonstrating that both exposures differen-tially contribute to sleep fragmentation. From a public health perspective, interventions to protect the sleep of populations near railway lines should therefore consider both exposure types.