A flight from Australia to Europe is easier than one from Europe to Australia.
Research from the University of Maryland suggests jet lag is not only based on distance travelled, but also the direction of travel.
Thanks to our biological clock, our brain responds better to a longer day from flying west across time zones than a shorter one from flying east.
For instance: a person flying west across 9 time zones can recover in less than 8 days, while a person flying east would need a little more than 12 days. The more time zones involved, the more the difference becomes.