Beat jet lag with light, exercise, and meal timing

You land at dawn in a city eight time zones ahead. The sun is rising. Your body insists it's midnight. By mid-afternoon, your eyes are closing at the dinner table. At 3 a.m., you're staring at the ceiling, mind racing, knowing you have a full day ahead. This is jet lag—the biological tax on long-distance travel, and it's unavoidable. But it's not unstoppable.

Jet lag happens because your body runs on a clock that doesn't care what the local time says. Dr. Nina Rzechorzek, who studies sleep and circadian rhythms at the University of Cambridge, explains it plainly: when you fly across time zones, your internal biological clock stays anchored to where you came from, even as you're trying to eat, sleep, and work on destination time. The mismatch creates a cascade of problems—fragmented sleep, daytime fog, irritability, poor focus, and digestive upset. Your body isn't broken. It's just confused.

The confusion runs deep. Nearly every cell in your body maintains its own 24-hour cycle, synchronized by a master clock buried in your brain. That master clock responds primarily to one signal: the daily rhythm of sunlight and darkness. When you cross an ocean and that rhythm suddenly shifts, your brain takes days to recalibrate. You're essentially a person operating on yesterday's schedule in today's world. Dr. Anna Edmondson, of the Laboratory of Molecular Biology at Cambridge, describes it plainly: your body is still stuck in the time zone you left behind.

Not all jet lag is equal. Flying east is typically harder than flying west, and there's a biological reason. Most people find it easier to stay up later than to fall asleep earlier—a quirk rooted in the fact that the human internal cycle naturally runs slightly longer than 24 hours. This gives us an innate bias toward delay rather than advance. Traveling west, you're working with your body's natural tendency. Traveling east, you're fighting it.

There is no cure, but the science offers real mitigation. Dr. Tatiana Wilson, a circadian researcher at Newnham College, Cambridge University, identifies three controllable levers: light, food, and movement. Light exposure in the morning shifts your clock earlier; light in the evening keeps you awake longer. The key is timing it right. Morning sunlight at your destination tells your brain to wake up sooner. Evening darkness tells it to sleep sooner. Indoor light, even on overcast days, is far dimmer than natural daylight, so stepping outside at the right time of day matters more than you'd think.

Exercise reinforces the shift. A walk during daylight hours in your new time zone signals to your body that this is when activity happens. Meal timing works similarly. Eating during the day and fasting several hours before bed helps regulate melatonin release—the hormone that makes sleep possible. Eating late at night can delay that release, pushing sleep further away.

Melatonin supplements are tempting but complicated. In the UK, melatonin is a prescription medication, available only under medical supervision. Even where it's sold over the counter, the actual dose in supplements can vary wildly from what the label claims, Edmondson warns. The safer path is the oldest one: good sleep hygiene. Go to bed at your target time. Keep your room dark and cool. Stick to your usual bedtime routine. These practices, combined with strategic light and movement, give your body the best chance to reset itself. The adjustment takes days, not hours. But it's possible.