It’s not easy to stay awake at the wheel when you’re a long-haul trucker. A 1935 National Safety Council paper found that some truckers “used an onion to moisten dry eyelids”; others, to keep from nodding off, “would light a cigarette and sleep until it burned down and awakened them by scorching their fingers.” Jimmy Hoffa once cited the latter strategy in arguing for why truckers should organize with his union, the International Brotherhood of Teamsters, which made its name on trucking. (The word “teamster” and the union’s logo featuring two horses come from the precolonial era’s horse-drawn buggy drivers who founded the union.)

Some truckers keep a bowl of ice water next to them while on the road so they can splash themselves in the face when they start nodding off. Famously, they also use chemical aids: as Commander Cody’s 1972 “Semi Truck” goes, “I took three bennies and my semi-truck won’t start,” and there are no lack of pop cultural references to pill-popping truckers. Another classic, from Dave Dudley’s “Six Days on the Road”: “I’m takin’ little white pills / And my eyes are wide open.” But drug and alcohol testing in the industry has led many to rely on legal alternatives like 5-hour Energy and Red Bull, available at any truck stop.

As Karen Levy shows in Data Driven: Truckers, Technology, and the New Workplace Surveillance, the problem is rooted in truckers’ pay structure, which is based on miles driven. That means that the many other tasks the job entails — fueling up, inspecting the truck, and loading and unloading (the latter, called “detention time,” can take several hours) — are unpaid. All that counts is distance. As the saying goes, “if the wheel ain’t turnin’, you ain’t earnin’.”