A dream holiday, an exotic destination, a long-haul flight, and finally some well-deserved rest. The problem is that many travelers arrive at their destination only to spend the first days of their vacation struggling with fatigue, sleep disturbances, low energy levels, and digestive issues. Researchers from Wroclaw Medical University point out that these symptoms may be caused by more than just classic jet lag. A growing body of evidence suggests that time zone changes also affect the trillions of bacteria living in our intestines.
This phenomenon, known as “gut jet lag,” describes a disruption in synchronization between the human biological clock and the rhythms of the gut microbiota. Although the concept is relatively new, researchers agree that our intestines may need just as much time as our brains to adapt to a new time zone.
Gut jet lag is a relatively new concept describing a state of desynchronization between the human biological cycle and the rhythms of gut bacteria. A short trip within Europe is unlikely to cause such major disruptions, but the problem becomes significant during long-haul flights that involve crossing multiple time zones ,- explains co-author Karol Biliński. – Under these conditions, fatigue and dietary changes can compromise intestinal barrier integrity and reduce the production of beneficial short-chain fatty acids.
Why do we feel worse after a long-haul flight?
Intercontinental travel means much more for the body than simply changing the time on a watch. Within a matter of hours, sleep schedules, meal times, light exposure, and stress levels all change dramatically. For the body, it is a major upheaval.
Our digestive system is extremely sensitive to these changes because the entire gut-brain axis operates according to a tightly regulated circadian rhythm. When biological signals become misaligned, communication between the intestines, immune system, and brain is temporarily disrupted ,- explains co-author Kacper Wiśniewski. – This temporary dysregulation is responsible for digestive complaints, poorer sleep quality, and reduced energy levels in many people during the first days after arrival.
This helps explain why the first days of a vacation are often the least comfortable. While the body is trying to adapt to new environmental conditions, gut bacteria may still be operating according to the schedule of the departure location.
When your gut cannot keep up with your journey
Many travelers experience constipation, bloating, a feeling of heaviness, or changes in appetite after arrival. Although local cuisine is often blamed, the underlying cause may be much more complex.
A sudden shift in meal timing directly affects the secretion of digestive enzymes, bile production, and gastrointestinal motility, says co-author Laura Rafner. – As a result, the balance of the gut microbiome may temporarily shift in favor of less beneficial bacterial strains. This can slow intestinal transit and lead to constipation and digestive discomfort.
The researcher notes that disruptions in the microbiota may also impair sleep quality, thereby worsening fatigue. This creates a vicious cycle that makes recovery from travel more difficult.
How not to waste the first days of your holiday
The good news is that the effects of jet lag can be reduced. Proper preparation before departure is crucial.
The key is to gradually adjust your biological clock to the destination time zone. This process should ideally begin several days before departure through appropriate management of light exposure and sleep schedules,- emphasizes co-author Paweł Witko.
Researchers also highlight the importance of chrononutrition, which means eating in alignment with the body’s biological rhythms. In practice, this means adopting the destination’s meal schedule before arrival.
While on the plane and after landing, meals should be consumed only during the daytime hours of the destination time zone, while eating during your biological night should be strictly avoided,- explains Paweł Witko. – It is also important to stay well hydrated and consider starting individualized probiotic and prebiotic supplementation before travel.
Melatonin may also be helpful, although the authors stress that its effectiveness depends heavily on the timing of administration.
The problem is not limited to travelers
Although the publication focuses on athletes traveling to competitions, its conclusions have much broader implications.
Studies involving shift workers and airline personnel suggest that ‘living against nature’—through shift work and irregular eating patterns—can significantly affect our microbiome, – says Dagmara Beata Gaweł-Dąbrowska, PhD, Professor at Wroclaw Medical University and head of the research team. – Maintaining good sleep hygiene, regular meal schedules, and appropriate exposure to daylight is not only important for athletes but forms the foundation of health for all of us.
In practice, similar mechanisms may affect millions of people who live in a constant state of time pressure, work shifts, or regularly disrupt their circadian rhythms.
Start your vacation by taking care of your biological clock
According to the researchers, preparing for a trip should involve more than booking flights, reserving hotels, and packing luggage.
To fully enjoy a vacation, we need to take care not only of our travel plans but also of our health,- summarizes Dr. Dagmara Beata Gaweł-Dąbrowska. – Long-distance travel is a major stressor for the body and can disrupt our internal clock. A conscious approach to our physiology may help us avoid spending the first days of a holiday battling fatigue and digestive problems, allowing us to enjoy our time away from the very beginning.
Vacations are meant to provide new experiences and renewed energy. However, growing scientific evidence suggests that to make the most of our travels, we should also remember the unseen passengers who accompany us wherever we go—the trillions of bacteria living in our intestines.
Take Care of Your Gut Before Your Vacation
Five Tips to Help Reduce Jet Lag
- Gradually shift your sleep schedule a few days before departure.
- Set your watch to the destination time zone as soon as you board the plane.
- Eat according to the local meal times of your destination.
- Stay well hydrated throughout your journey.
- Limit exposure to light and screens during your biological night.