Can the effects of jet lag ever really be cured?
Even the most experienced flyers can be grounded by the effects of long flights. Kim Bielenberg considers some possible solutions
It affects the concentration of politicians and golfers, and is believed to increase the risk of serious illness including cancer and heart attacks.
So far nobody has come up with a definitive cure for jet lag, but there are popular new smartphone apps that claim to help.
The effects of long flights could even be seen with an experienced flyer like the US Secretary of State John Kerry when he arrived in Poland recently.
The luxurious bedding of Air Force One on the flight from America did not protect him from fatigue. When he met the Polish president Bronislaw Komorowski, he was seen nodding off.
Ronald Reagan famously arrived at far-flung locations looking as fresh as a daisy. Along with the CIA and the US Army, he swore by the "anti-jet lag diet", which involved alternating between fasting and feasting in the days before flying.
Jet lag amounts to a series of symptoms that occur when our internal body clock is disrupted.
The former pilot Michael Comyn, an expert in fear of flying, believes there are several ways in which long haul passengers can stave off the worst effects of jet lag.
"Aer Lingus pilots who are flying to America avoid it by staying on Irish time," says Comyn. "There are other ways of adjusting by adapting to the light at your destination and food also plays a role."
There are several apps now available that offer advice on how to make the adjustment across time zones, and they often involve regulating light.
Most experts now advise that flyers can avoid some jet lag by adjusting their sleeping pattern to the country of their destination in advance.
New York, for example, is five hours behind Ireland. So, travellers are advised to prepare by going to bed gradually later in the days before departure.
If you are coming to Ireland from America, the opposite applies and travellers are advised to prepare by going to bed at 8pm.
Recently, a new smartphone app called Entrain was launched. Devised by mathematicians, it helps users to adjust to time zones by regulating light.
Light is the most significant factor in establishing circadian rhythms. The app uses complex equations to determine when and for how long the user should be exposed to brightness.
Prompted by the app, the user specifies the length of the trip and the destination city. Entrain then calculates the best light exposure schedule for the fastest possible adjustment, as well as estimating how long it will take to adjust.
The researchers who devised the app calculated schedules for more than 1,000 possible trips.
Some travellers use a lighting device such as the Philips GoLite Blue. According to Philips, turning on the light at certain specified times helps the body to adjust.
Few individuals have to cope with jet lag as much as professional golfers, as they fly from tournament to tournament.
Padraig Harrington has said he finds it harder when he comes home, because he copes better when he has to meet specific time commitments.
He recommends plenty of time in the gym to keep the effects of flying at bay. However, doctors advise travellers to avoid strenuous exercise within two hours of trying to sleep.
Harrington also advises travellers not to turn the television on if they wake at 3am.
"Just lie there and look at the four walls. The minute you put on the television, that's it. You're never getting back to sleep."
Harrington has said one night of sleep deprivation has no effect on his performance whatsoever, while two nights is extremely detrimental.
Some travellers swear by melatonin, which is now available only on prescription.
Normally, the brain produces melatonin during the night to help with sleep. The body starts to make melatonin when it gets dark, and stops when it gets light. The melatonin that's sold as a treatment is a man-made version of this hormone.
Melatonin is said to work best if you take it between about 10pm and midnight (destination time).
However, it should be noted that its use for jet lag is not advised by the World Health Organisation (WHO), which says: "Manufacturing methods are not standardised: the dose per tablet can vary considerably and some harmful compounds may be present."