Bryan Johnson, the US tech entrepreneur known for his anti-ageing experiments and strict health tracking routines, has claimed that international travel may be doing more harm to the body than people realise. In a recent post shared on X, Johnson described modern travel culture as misleading and said his own health data showed serious disruptions after a trip to Asia.Calling travel “kind of barbaric for the body”, Johnson shared three specific findings that appeared in his biometric readings after the journey. According to him, the effects lasted for days and in some cases more than two weeks.Finding 1: Blood glucose stability took 9 days to returnJohnson said one of the biggest changes was seen in his blood glucose regulation after travelling internationally. He revealed that it took “9 days for blood glucose stability” to return to normal after the Asia trip.Blood glucose stability is often linked to metabolism, energy balance and overall recovery. Sudden changes in sleep schedules, food timing and stress levels during travel are believed to affect how the body processes sugar. Johnson suggested that crossing time zones and disrupting the body clock may have contributed to the delayed recovery.Finding 2: Circadian rhythm remained disturbed for over a weekThe entrepreneur also said his internal body clock struggled to adjust after the trip. According to the post, it took “9 days to re-entrain my circadian rhythm”.Johnson explained that the body functions on a timing system controlled largely by sunlight exposure and sleep cycles. When those patterns are disrupted through long-haul flights and changing time zones, the body may take several days to return to its normal rhythm.He added, “The body understands time zone changes as trauma,” while arguing that modern life has normalised something that may actually put heavy stress on biological systems.Finding 3: Sleep architecture recovery took 18 daysAmong the three findings, Johnson said sleep recovery took the longest. He claimed it required “18 days for sleep architecture recovery” after returning from Asia.Sleep architecture refers to the structure and quality of sleep, including deep sleep and REM cycles. According to Johnson, travel-related stress and jet lag disrupted these patterns for more than two weeks.He also pointed toward aircraft cabin conditions as a possible reason. In the post, he wrote that cabin altitude is usually maintained at around 7,000 feet, which may create mild oxygen deprivation or hypoxia. He claimed this can affect cortisol levels and suppress melatonin production even after landing.— bryan_johnson (@bryan_johnson) Bryan Johnson links frequent travel to other health concernsApart from sharing his own measurements, Johnson also referred to studies connected to frequent travel. He wrote that people who travel for work more than three weeks a month reportedly show higher levels of anxiety, depression and alcohol-related problems compared to those who travel less.He further claimed that repeated jet lag has been linked to shrinkage in memory-related areas of the brain among airline crews. Another issue he highlighted was the dry air inside aircraft cabins. According to Johnson, low cabin humidity dries out mucous membranes that normally help block infections, potentially making travellers more vulnerable to illness.Johnson also shared his personal recommendation for international travel frequency. He suggested limiting long-distance trips to “no more than once every 3 months”, adding that research indicates the body may need roughly one day per time zone crossed in order to recover properly.