Could you experience jet lag before airplanes existed? Did passengers aboard the Titanic suffer from it? Could ancient Roman travelers get jet lag? And how fast would you actually have to travel to outrun your body's internal clock? Today on Smartest Year Ever, I'm tracing the surprising history of jet lag—from ancient Rome and transatlantic ocean liners to record-breaking steam trains, early aviation, and the invention of the phrase "jet lag" itself. Along the way, we'll explore the science of circadian rhythms, why traveling east affects your body differently than traveling west, how Earth's rotation creates differences in solar time, and why your biological clock struggles to adjust when you cross time zones. We'll investigate the Titanic's unusual shipboard clocks, the record-setting RMS Mauretania, a spectacular 1905 train journey orchestrated by a notorious con man, and a sleep scientist who spent weeks underground trying to change his body's natural rhythm. And I did the math to answer a question I couldn't stop thinking about: What is the actual speed at which you begin to outrun your body clock? The answer is far more surprising than you might expect. We'll also uncover how early pilots and airship passengers experienced time-zone fatigue before commercial jet travel became commonplace—and how the term jet lag finally entered our vocabulary. If you've ever wondered what causes jet lag, why flying east is harder than flying west, how time zones work, or when humans first experienced jet lag, this is a journey through the fascinating intersection of history, astronomy, transportation, and sleep science. SOURCES Titanic & Ocean Liners Encyclopedia Titanica. (n.d.). Titanic: Time altered. National Library of Wales. (1909). Fishguard's red-letter day: Mauretania arrives. The Science of Jet Lag Boulos, Z., et al. (1995). Light treatment for sleep disorders: VII. Jet lag. Journal of Biological Rhythms. Aschoff, J., et al. (1975). Re-entrainment of circadian rhythms after phase-shifts of the zeitgeber. Chronobiologia. Czeisler, C. A., et al. (1999). Stability, precision, and near-24-hour period of the human circadian pacemaker. Science. Centers for Disease Control and Prevention. (n.d.). Jet lag. In CDC Yellow Book. Ancient Travel & Railroads Stanford University. (n.d.). ORBIS: The Stanford geospatial network model of the Roman world. The New York Times. (1883). A quiet change to the standard time. California State Railroad Museum. (n.d.). Death Valley Scotty's race for glory. The Human Body Clock National Park Service. (n.d.). Dreaming underground: The Mammoth Cave sleep study. Early Aviation Mohler, S. R., Dille, J. R., & Gibbons, H. L. (1968). Circadian rhythms and the effects of long-distance flights (FAA Report AM 68-8). Post, W., & Gatty, H. (1931). Around the world in eight days. Fédération Aéronautique Internationale. (2019). Ninety years since the first round-the-world airship flight. Airships.net. (n.d.). Hindenburg 1936 flight schedule. Where the Name Came From Smithsonian National Air and Space Museum. (n.d.). When did the term "jet lag" come into use? Sutton, H. (1966, February 13). Discussion of jet lag. Los Angeles Times. Music thanks to Zapsplat. #JetLag #sciencefacts #historyfacts #travel #LearnOnSpotify