Flying places the body under significant physiological stress, including bloating, fatigue, and dehydration. While not dangerous for healthy travellers, these effects are common. Blood oxygen levels drop from about 97% to 90% due to cabin pressurisation, which can cause fogginess and tiredness. The dry air, with humidity as low as 10-20%, evaporates moisture from skin, eyes, nose, and throat, though whole-body dehydration is a myth. Gas expansion under Boyle's Law leads to bloating, and cabin pressure dulls taste, making savoury flavours more pronounced.
Pre-Flight Stress and Psychogeography
Airports act as liminal zones, creating disorientation and raising stress hormones before boarding. Steve Taylor, Senior Lecturer in Psychology at Leeds Beckett University, explains that losing control over time can cause anxiety, elevating stress levels.
In-Flight Physiological Changes
Pharmacist Thorrun Govind notes that cabin pressure mimics an altitude of 6,000-8,000 feet, reducing blood oxygen to 90%. This impairs cognition, causing fatigue. Dry air affects external surfaces, not whole-body hydration. Alcohol exacerbates fluid loss, leading to headaches. Taste perception changes: sweet and salty are suppressed, while savoury is enhanced, explaining the popularity of tomato juice.
Post-Flight Bloating and Ear Popping
Trapped gas expands as cabin pressure falls, causing bloating. Ear popping results from pressure rebalancing in the middle ear and sinuses.
Tips for Frequent Flyers
Thorrun Govind recommends moving regularly, staying hydrated, limiting alcohol and caffeine, and protecting sleep. Compression socks and daylight exposure after landing help. Wellness expert John La Puma advises assuming the destination time zone immediately and getting outdoor daylight before coffee or phone use.
