You've landed at LAX and the wall-clock says 9am. That's a few hours before you left Melbourne yesterday. Despite your eyes telling you it's time to start the day, your brain swears it's four in the morning. Tomorrow.
Welcome to the world of jet lag, a bleary-eyed place of fatigue and poor function.
For as long as crossing time zones at near-supersonic speed has been causing jet lag, long haul pilots have had to contend with its effects – and keep functioning.
Gary King is a Qantas A380 Captain with 31 years of flying experience, so he's had his fair share of jet lag – not that that makes jumping time zones any easier.
"Nothing 'beats' jet lag," he says. "Although the effects can be minimised."
Accepting the inevitable
And after 34 years in the cockpit, Captain Mark Ford, who also flies A380s with Qantas, says jet lag becomes more familiar with experience.
"Broken sleep and a general lethargy are the main effects for me," he says.
So by combining what's known about the science of jet lag with the years of practical experience of some of Australia's most experienced pilots, here are a few tips for the busy traveller to make jet lag that little bit more bearable.
Qantas Captain and pilot for the past 38 years, Peter Probert tries not to shift time zones at all for short trips.
"Between flights, I actually try to stay on Sydney time to lessen the effects of jet lag," he says. And many travel medicine guidelines agree with him.
Jet lag happens when there's disconnect between the external light-dark cycle of night and day and our internal circadian rhythm aka the body's internal clock.
Because it takes time to readjust the circadian rhythm to a new time zone, it may be easier to schedule meetings and important events at a time that coincides with daytime at home and avoid the pain altogether.
Virgin Australia 777 Captain and fleet standards manager Paul Halpin says that adjusting to a new time zone is easier when travelling westbound. He's been flying for 36 years, 31 of them as a commercial pilot.
"West is best," he says, echoing the well-worn travellers' motto.
There's a physiological explanation for this experience. When you travel west, your body clock has to be delayed to adjust to a new time zone. Most people find this easier to settle into than travelling east, where advancing the circadian rhythm is required.
Captain Probert agrees, "Flying east drives wanting to sleep during the day with subsequent awake periods during the night," he says.
But, regardless of the direction of travel, the greater the time zone shift, the worse the effect adds Qantas Captain Gary King.
"The twelve hour time zone change between London and the east coast of Australia is about as bad as it gets," he says.
Get some sun, some shade (and maybe take some melatonin). Especially after long eastward flights.
The two most important things controlling the circadian rhythm are melatonin and exposure to light. Strategic exposure to light and dark, combined with melatonin supplementation may help some travellers adjust to a new time zone more quickly.
Under normal circumstances melatonin levels start to rise in dim light, around two hours before sleep. It then keeps rising until it's at its highest point three hours prior to waking. By morning, it has usually dropped to undetectable levels.
By gaining exposure to bright light during the day of arrival and then restricting light in the evening combined with a dose of melatonin, the theory goes that the circadian rhythm can be kick-started into better sync with the new time zone.
Have a drink ... of water
Sorry to spoil the party, but alcohol and caffeine worsen dehydration which worsens the effects of fatigue, no matter how far you're going or how many time zones you cross.
While some people may get some benefit from caffeine as a stimulant, it's often offset by its sleep disturbing effects at the other end of the day.
And avoiding caffeine and staying hydrated is "rule number 1" for Virgin's Paul Halpin, a rule also shared by Gary King at Qantas.
"On a long flight I'll drink two and a half to three litres of water," says King.