Circadian sleep propensity and alcohol interaction at the wheel

OBJECTIVES: The study was aimed at estimating the effect of alcohol consumption, time of day, and their interaction on traffic crashes in a real regional context. METHODS: Blood alcohol concentration (BAC) data were collected from drivers involved in traffic accidents during one year in an Italian region and in a control group of drivers over the same road network. Mean circadian sleep propensity was estimated from a previous study as function of time of day. Accident risk was analyzed by logistic regression as function of BAC and circadian sleep propensity. RESULTS: BAC values greater than zero were found in 72.0% of the drivers involved in crashes and in 40.4% of the controls. Among the former 23.6% of the drivers exceeded the BAC legal threshold of 0.05 g/dL, while illegal values were found in 10.4% of the controls. The relative risk showed a significant increase with both BAC and circadian sleep propensity (as estimated from time of day) and their interaction was significant. CONCLUSIONS: Due to the significant interaction, even low BAC levels strongly increased accident risk when associated with high sleep propensity.Copyright © 2016 American Academy of Sleep Medicine. All rights reserved. Language: en