A recent Guinness World Record-breaking flight lasting just over 24 hours has highlighted the physical challenges of ultra-long-haul travel. The flight, part of the Airbus A350-1000ULR test campaign for Qantas Airways' Project Sunrise, departed Melbourne, Australia, and landed in Toulouse, France, covering 12,503 nautical miles. While no paying passengers were on board, Qantas plans to launch the route in 2027, promising London to Sydney in just 22 hours.
How the Body Reacts in the First Hours
According to Dr Nikki Ramskill, private GP and founder of The Female Health Doctor, the body undergoes distinct phases during a long-haul flight. In the first four hours, prolonged sitting with knees bent reduces the calf muscles' ability to pump blood back to the heart, leading to blood pooling in the lower legs and swollen ankles and feet.
Between hours four and eight, the cabin environment takes its toll. Cabins are pressurised, but the pressure is lower than at sea level, resulting in a slightly lower oxygen concentration. Most healthy people cope with this, but the dry air can cause dry eyes, nasal passages, skin and mouth. Cabin pressure changes can also expand gas in the digestive tract, causing bloating, discomfort or gas. Sitting still can lead to stiffness in the hips, lower back and neck.
Fatigue and Discomfort in the Middle Hours
From eight to twelve hours, fatigue and sleep disruption become noticeable as circadian rhythms clash with the environment. "Our circadian rhythm dictates when we feel sleepy, alert and hungry," says Dr Ramskill. Poor sleep can leave passengers irritable, emotionally sensitive, forgetful and less able to concentrate.
After twelve hours, stiff muscles, swollen feet, general fatigue and discomfort set in. Dr Ramskill stresses the importance of moving to maintain circulation, as inactivity increases the risk of venous thromboembolism (DVT and PE). For most healthy travellers, the risk is very low, but certain medical conditions and individual risk factors, such as pregnancy and use of oral oestrogens, can make a considerable difference.
Final Hours and Recovery Tips
In the last six hours, passengers may feel physically and mentally drained, with symptoms including swollen ankles, muscle stiffness, digestive upset, headaches, poor concentration and disorientation from crossing multiple time zones. Fatigue is not just about how long you've been awake, but also when your body thinks you should be asleep.
Dr Ramskill advises passengers to get up and walk around regularly every one to two hours, do ankle circles, calf contractions and foot pumps while seated, and drink water regularly while avoiding excessive alcohol. Those at increased risk of DVT should consider properly fitted graduated compression stockings as per their doctor's advice. To minimise jet lag, she recommends gradually shifting sleep schedules before departure, adapting to the destination's time zone during the flight, and getting natural daylight after landing.
Qantas' Plans for Passenger Comfort
Qantas has been working with scientists at the University of Sydney to minimise jet lag on ultra-long-haul flights. According to Rhys Jones, Aviation Editor at frequent flyer website Head for Points, exposure to light at the right times is critical to resetting the body clock. The airline will implement a protected dark 'night' period plus daytime periods, and offer special jetlag-busting meals, including blander meals before bedtime and spicier, more flavourful meals after sleep. A Wellness Zone will allow all passengers, not just those in first or business class, to stretch and move, helping to reduce the risk of blood clots.
