Jet lag may be a small price to pay for international travel, but for frequent fliers, it can take a real toll. When your internal clock is at odds with the local time, that foggy-headed feeling after a long-haul flight is more than just a travel nuisance: It’s a legitimate physiological condition, one that affects sleep quality, digestion and mood. Known as circadian desynchrony, jet lag occurs when the body’s internal 24-hour rhythm, or circadian clock, is disrupted by rapidly crossing multiple time zones. While some travelers can adjust within a day or two, others struggle for a week or longer, depending on factors such as direction of travel, age and personal sleep habits. The body’s circadian clock is regulated by environmental cues, primarily the rising and setting of the sun. When a person travels across time zones, this internal clock struggles to adjust to the new light-dark cycle. The result is a delay between the internal clock and the external environment, hence the term "jet lag."

Traveling eastward tends to cause more severe symptoms than westward travel because advancing the sleep-wake cycle is generally more difficult than delaying it. For example, flying from Los Angeles to London may lead to greater disruption than flying the same distance in the opposite direction. On average, the body needs approximately one day per time zone crossed to adjust fully. Preventing jet lag begins before departure. Gradually shifting sleep and wake times to align more closely with the destination’s time zone can help reduce the shock to the system. This adjustment can start anywhere from three to five days before travel and by moving bedtime and wake time earlier or later by 30 to 60 minutes per day, depending on the direction of travel. Proper sleep in the days leading up to a flight is also beneficial. Getting adequate rest before travel helps build resilience against sleep deprivation and fatigue. Staying well-hydrated and avoiding alcohol or excessive caffeine can further support better sleep quality. Aligning in-flight behavior with the destination’s time zone can also ease the transition. If it is nighttime at the destination, attempting to sleep during the flight can help the body adjust. Using an eye mask, neck pillow and earplugs or noise-canceling headphones can make it easier to rest in transit. In addition, it’s important to stay hydrated during the flight, as airplane cabins have low humidity levels that can lead to dehydration, thereby worsening fatigue. Drinking water regularly and avoiding diuretics, such as alcohol and caffeinated beverages, can mitigate this effect.

Upon arrival, it is imperative that travelers adapt to the local schedule as soon as possible and exposure to natural light is one of the most effective ways to reset the body’s internal clock. Spending time outdoors during daylight hours, particularly in the morning, can accelerate this adjustment. Physical activity can also help reduce feelings of lethargy. Even light exercise, such as walking or stretching, promotes alertness and can support the transition to the new time zone. It is generally advised to avoid long naps upon arrival. While short naps of 20 to 30 minutes may provide temporary relief, sleeping for longer periods during the day can delay adaptation and interfere with nighttime sleep. Eating meals at local times further reinforces the new schedule. Sticking to a consistent routine for sleeping, eating and waking helps train the body to adjust more quickly. Some travelers recommend avoiding screen usage in the evening and adding a melatonin supplement to help shift their sleep cycle. Melatonin is a hormone naturally produced by the body in response to darkness. Taking a low dose an hour before intended bedtime at the destination may assist in resetting the circadian rhythm.

However, timing and dosage are important. Melatonin is most effective when used for short durations and as part of a broader strategy that includes light exposure and behavioral adjustments. Overuse or incorrect timing may lead to further disruption. Other over-the-counter or prescription sleep aids may help with temporary sleep difficulties, but these should be used cautiously and typically under medical supervision, as they can carry side effects and do not address the root causes of jet lag. Recovery from jet lag varies from person to person, but most travelers begin to feel better within a few days. By maintaining healthy habits in the midst of travel, individuals can reduce the severity and focus on enjoying their trip.