You might assume lack of sleep is the main cause of jet lag. “But it's really about your circadian rhythm, your body's internal clock,” says Dr Nichola Conlon, a molecular biologist and longevity expert. “When you cross time zones quickly, your internal clock is still running on home time while the world around you has moved on. That mismatch is what leaves you feeling groggy and out of sync.” 

To get the jump on jet lag, preparation is key. “Start to shift your sleep schedule a few days before you fly,” says pharmacist and preventative health and longevity specialist Dr Dorsa Jalaei. “Moving bedtime 30 to 60 minutes per day towards the destination time gives the body clock a head start, so you land partly adjusted rather than starting from zero. The clock can only shift about an hour a day on its own, which is why a long eastward jump, for example, feels so brutal: you are asking it to do something it physically cannot rush.”

“Light sets your body clock, so getting the right kind at the right time makes a real difference,” says Nichola. According to Dr David Jack, a medical doctor, “Light is the most powerful regulator of the circadian system. Exposure to bright morning light (towards the blue end of the visible spectrum) helps advance your body clock, making it easier to adapt when travelling east.” If you’re travelling west (New York from London, for example), “Evening light (more towards the red spectrum) tends to delay the clock and reset your rhythm.” Even a short walk outdoors after arriving can help signal to your brain which time zone it should be operating in.

As a private jet pilot, Patrick Biedenkapp has four ways to alleviate jet lag. First, “Hydration is one of the most important and most overlooked factors. Aircraft cabins are incredibly dry, so I make a conscious effort to drink plenty of water before, during and after a flight.” He also suggests avoiding alcohol: “It disrupts sleep quality, increases dehydration and almost always makes jet lag worse.” On arrival, create a better sleep environment: “For better sleep, I use noise-cancelling headphones, a cooling eye mask, and keep the room as dark and cool as possible.” Finally, pay attention to nutrition: “Avoid large, heavy meals before and during flights, and focus on nutrient-dense choices that provide stable energy levels.”

“Our metabolic systems are closely linked to circadian rhythms,” explains David, “so eating according to your destination's mealtimes, even if you're not especially hungry, can help reinforce the new time zone.” Don’t necessarily follow the in-flight meal schedule, advises Nichola. “It might mean skipping a meal or eating at an odd time, but shifting your meals to fit your destination time zone helps shift your digestion and metabolism into the right rhythm."

If you’re on an early flight, coffee might be required, but Dorsa advises stopping there. “Caffeine blocks adenosine, the molecule that builds up through the day to make you sleepy. But caffeine has a half-life of around five to six hours, so an afternoon cup is still half-active at bedtime and will fragment the sleep you need to consolidate the shift.” 

A popular over-the-counter medication in the US, melatonin acts as a timing signal rather than a sedative. “A small dose (up to 3mg) in the early evening at your destination nudges the clock in the right direction, most usefully for eastward travel when crossing five or more time zones,” says Dr Dorsa. It’s worth noting that melatonin is prescription-only here in the UK.

“If I'm only staying for a very short layover before heading home again,” says Patrick, “I often try to remain closer to my home time zone. Constantly switching back and forth can sometimes create even more fatigue than staying on your original schedule.” 

“When you cross six, eight or even ten time zones, your circadian rhythm simply cannot adjust instantly,” says Patrick. “Some degree of jet lag is inevitable, so it isn't something you completely eliminate – it's something you manage. Good sleep habits, smart nutrition, strategic light exposure and a little patience are the most effective tools we have.”