Every road-tripper knows the feeling: a few hours into the drive to the trailhead or campsite, you're stiff, foggy, and weirdly exhausted despite doing nothing but sitting. Experts told Outside why that happens — and the fixes are simpler than you'd think.
The drowsiness is the most dangerous part. John Gaspar, who studies human factors at the University of Iowa's Driving Safety Research Institute, explains that long drives are simultaneously understimulating (endless straight road) and overstimulating (constant navigation and traffic stress), a combo that wrecks alertness. Worryingly, he says microsleeps — where drivers nod off for several seconds — can kick in within the first 90 minutes, especially if you're already short on sleep. And the classic countermeasures? Cranking the music, opening a window, blasting the A/C. Gaspar says research shows these tricks have little to no real benefit. The only reliable cure is stopping to rest, even for 10 to 20 minutes.
Your muscles take a hit too. Dr. Brian Cervoni Rosario, a sports medicine physician at Boston Medical Center, notes that neck and shoulders suffer most, because drivers constantly stabilise their head against the car's motion while staring ahead — a sustained muscle contraction that builds up over hours. Add traffic tension and the picture gets worse. Car vibrations also amplify stress on the lumbar and cervical spine, and a 2022 study of taxi drivers found that vibration alone measurably reduces handgrip strength. Meanwhile your legs are doing small, repetitive contractions on the pedals, and prolonged sitting compresses your back, thighs, and glutes into stiffness.
Then there's the gut. Gastroenterologist Dr. Rudolph Bedford points out that when you don't move, your bowels don't either — constipation, bloating and gas are practically an occupational hazard for professional drivers, and a cinching seatbelt doesn't help. Typical road snacks make it worse: gas-station food tends to be low in fibre and high in fat and salt, all of which slow digestion, while soft drinks, sugar-free gum and caffeine add to the abdominal grumbling. The CDC also warns that long stretches seated in vehicles raise the risk of blood clots.
The good news: the fix for nearly everything above is the same. Pull over. Gaspar says rest stops are the only thing that genuinely restores alertness, and Bedford recommends stopping every two to three hours to walk for five to ten minutes — it gets your circulation going and keeps your digestive system moving. If it's not safe to get out, even twisting your torso and flexing your ankles in the car helps.
For anyone planning a driving holiday, this is the kind of advice worth building into the itinerary. Yes, extra stops make the trip longer. But arriving at your destination alert, unblocked, and without a wrecked back is a decent trade. Schedule breaks into the route rather than treating them as failures — your last two hours of driving will thank you.
