On long-haul flights a deficiency in the blood can occur. Flights are at altitudes between twenty-five thousand and sixty thousand feet, at heights with too little oxygen to sustain human life. To make the air breathable, air outside the plane has to be compressed by the engines before being pumped into the cabin.
Farrol Kahn, a medical author and director of the Aviation Health Institute agrees that jet lag disrupts the body’s circadian rhythms and is caused by long-haul travel, but adds another important factor is the lower level of oxygen in aeroplane cabins.
‘There is 20-25 per cent less oxygen in the cabin when you fly and that’s really the cause of jet lag’. Lack of oxygen impairs both physical and mental performance, he points out.