Jet lag is an often unavoidable effect of long-haul travel, and it can affect the body in a number of ways, from sleep and mood to digestion.
The condition occurs when the body's internal clock, which governs cycles of sleep and wakefulness, falls out of step with the local time at a traveller's destination.
Common symptoms include difficulty sleeping at night, daytime tiredness, poor concentration, irritability and stomach problems.
“Light is the most powerful tool we have for resetting the body clock after a long flight.”
Travelling east is often considered harder than travelling west, because it requires the body to shorten its day rather than lengthen it.
“The body's clock adjusts gradually, typically by around an hour or so a day, so long trips across many time zones can take several days to recover from,” said one sleep scientist.
Experts recommend adjusting sleep times gradually in the days before departure and seeking natural daylight at the right times after arrival to help reset the body clock.
Staying hydrated, limiting alcohol and caffeine during the flight, and eating meals according to local time at the destination can also help.
Short naps may relieve tiredness but should be kept brief, so they do not make it harder to sleep at night in the new time zone.
Frequent travellers and airline crew often develop personal routines to cope, such as staying on home time for very short trips, and experts say planning ahead can make a noticeable difference to how quickly people feel themselves again.
Some travellers consider supplements to aid sleep, but experts advise speaking to a pharmacist or doctor before using them.
