Today Woody Will Smith of Dayton, Kentucky, goes on trial for strangling his wife to death with an electrical cord last year. His defense: The caffeine made him do it. MSNBC reports that Smith "was drinking five or six soft drinks and energy drinks a day, along with taking diet pills; it all added up to more than 400 milligrams of caffeine a day." That's equivalent to about four cups of coffee per day, which I used to consume on a regular basis when I worked in an office. For the record, I never murdered anyone. Until now I did not realize how close I came.
Judging from the comments of a psychologist hired by the defense, Smith's argument is that he suffered a temporary psychosis caused by sleep deprivation. According to MSNBC, Smith told the psychologist that in the weeks preceding the murder he "hadn't been sleeping, in part out of fear his wife would take their two children and leave him." So even if you accept that Smith's judgment was impaired by lack of sleep, it's not clear the caffeine was the cause. Assuming it was one of the things that kept him up at night, he chose to consume it, so he is responsible for its contribution to his insomnia. And not to put too fine of a point on it, but insomniacs typically do not kill their wives.
I suspect the notion of a caffeine-crazed killer will strike most people as risible, since caffeine is a very familiar drug—the most popular psychoactive drug on the planet, in fact. Yes, too much can make you jumpy and keep you up when you want to sleep. But drive you to murder your wife? You've got to be kidding.
People are much more credulous about such tales when they involve less familiar drugs such as crack, PCP, or methamphetamine. As I show in my book Saying Yes, claims that such drugs turn people into killers, like similar stories that were told about marijuana in the 1920s and '30s, have little basis in fact. But my favorite example is qat, since this stimulant shrub has for centuries served a function similar to coffee in places such Somalia, Ethiopia, and Yemen. This long history of socially integrated use did not prevent outlets such as The New York Times, The New Republic, and The Washington Times from running stories in the early 1990s implying that qat chewing played a significant role in Somalia's civil war. If the country's feuding gunmen had been drinking coffee instead of chewing qat, editors at these publications probably would have been a bit more skeptical of such claims.