A Rare Case of Drunk Driving in Japan: Alcohol-related Sleepwalking

Alcohol has been identified as a potential precipitating factor for parasomnia, particularly sleepwalking (SW), which categorized in a classic form of non-rapid eye movement sleep arousal disorder. The police consulted us regarding the association between alcohol consumed, blood alcohol concentration, and the behavior of a drunken driving suspect with complete memory loss. We report a rare case of a Japanese drunk driver who possibly experienced alcohol-related SW, based on the statements of the suspect, pharmacokinetic analyses of breath alcohol concentration, testimonies of the witnesses, driving recorder data, and medical records. We concluded that the suspect should be considered non-compos mentis when the drunken driving offense was committed because he might not have been able to control his behavior while in a SW state. However, if he again commits crimes during SW under the influence of alcohol, the crimes should not be excusable because he is now aware of his alcoholrelated complicated characteristics.