Should DUI become DUIA?

Three letters can be deceptively simple. DUI = driving under the influence [of] alcohol or some other substance that prevents you driving safely. In the USA, ambien is the best-selling sleeping pill. So should it be DUIA "driving under the influence of ambien"? In real-world CSI labs around the US, ambien makes the top-ten of most identified "drugs" found in people arrested for traffic offences. Fascinatingly, some drivers claim this was "sleep driving".

Step aside "sleepwalking". You have new competition.

Almost all those arrested say they have no memory of getting up or of driving. These are the "ambien drivers". Now let us be clear. Ambien has not suddenly become unsafe. It has been on the market for thirteen years and there are few problems so long as people follow the manufacturer’s directions. But there were twenty-six million prescriptions written in the US last year, and more ambien was bought through online pharmacies. So we should not be surprised if a few people do habitual things when not quite awake.

If you look at the label on an ambien bottle or read the accompanying notes, you will see a clear warning that ambien can cause sleepwalking. The same effect is possible from alcohol so, in equally plain words, the label tells people not to mix alcohol and ambien. Wait a minute! Let us be cynical for a moment. Is this use of ambien a trick to create a defence to DUI? When involved in an accident, do drivers pop a quick ambien tablet into their mouths?

For once, this kind of behaviour seems unlikely. There is a pattern to the accidents where ambien is a factor. The drivers have failed to control the car in a spectacular way, e.g. by hitting parked cars or traffic signs on otherwise empty roads. They sit passively in the car after the accident. They make no response when approached by the police. At the March meeting of the American Academy of Forensic Science, a research paper reported cases of extreme driver impairment often with ambien either at overdose levels or mixed with other medications. This made the ambien sleep-driving explanation a plausible defence.

People affected by sleep disorders can act in unusual ways, particularly in the intermediate stage between sleep and being awake. If there is still some ambien active in the body, people do things around the house and have no memory of it the next day. It should not surprise us if, occasionally, this extends to driving. However, although forensic scientists have begun to talk more openly about the issue, it is still not possible to gauge the exact extent of the problem because only twenty-four states in the US routinely test blood samples from traffic accident cases.

Does this mean that ambien should have a stronger or more prominent warning label? At present, there is not enough evidence to suggest this is necessary. Although there are a few DUI cases involving ambien, there is no clear national pattern. The FDA has admitted to receiving forty-eight reports of adverse events arising from the use of ambien in 2004, but only one related to a traffic accident. Further, if there were so many ambien-related incidents, the news media would be full of stories and editorials demanding action. As it is, cases are noticed because they are still relatively unusual.

Why do these things happen? In some cases, it is almost certainly human nature. People forget the warnings, particularly about taking ambien after drinking alcohol, or they do not believe the warnings are serious. But a few people do find strange things happening to them. In 2001, the Mayo Clinic Sleep Disorders Center reported five cases where people had risen from their beds and eaten midnight snacks. But, so far, sleepwalking seems to affect only a tiny proportion of the millions of people who take ambien.

Nevertheless, I would feel more confident on the road if state and federal governments around the world did routinely test blood samples from everyone involved in traffic accidents. As more and more people take medications like ambien, whether for therapeutic or recreational purposes, I would like to know what the risk of being injured by a drug-impaired driver really is.