Do lower oxygen levels in planes contribute to jet lag?

This time on Question of the Week, Mark wants to know what effect lower levels of oxygen in aeroplanes might have on how we feel after a flight, and what impact the smoking ban might have had. As a follow up, he wonders about jet lag and whether it's possible to suffer its consequences after a long haul flight to somewhere in the same time zone. James Tytko asked Malcom von Schantz, Professor of chronobiology at Northumbria University, for help with the answer...