Frequent air travellers, such as cabin crew who repeatedly take long-haul flights, risk ill health, a study says.
There are measures that can help the body clock to adjust
As well as the obvious jet lag encountered with crossing multiple time zones, an out-of-kilter body clock can trigger psychotic and mood disorders.
The researchers say disrupted sleep and hormone patterns are largely to blame, The Lancet reported.
The Liverpool John Moores University team reviewed over 500 published articles on aviation and health.
They found reports of cabin crew experiencing decreased cognitive performance and mental health problems, including brief episodes of psychosis - loss of contact with reality.
And air hostesses complain of menstrual cycle problems linked with the irregularity of their work.
The study authors, Jim Waterhouse and colleagues, offer tips to limit travel fatigue and jet lag, such as deliberately seeking or avoiding light at the new destination to help the body clock adjust.
Having a strong cup of coffee and taking some exercise can help with staying awake when the body's reserves are flagging, they add.
JET LAG SYMPTOMS
Headaches, fatigue and irritability
Indigestion and altered appetite
But they stress there is no cure to prevent jet lag and caution against the use of unlicensed drugs such melatonin - the hormone secreted during sleep.
They advise that if a journey crosses fewer than three time zones, then jet lag is unlikely to be a major problem for most.
And if the stay is too short - fewer than three days generally - for the body clock to adjust, it is best to remain on "home time".
If the journey is across more than three time zones and the stay is more than three days, then it is worth switching sleep and activities to the new destination's time.
Flights east generally cause worse symptoms than those westbound, they say.
As a rule of thumb, with eastbound flights the number of days needed to recover is equal to two thirds of the time zones crossed. With westbound flights the number is half the time zones crossed.
A spokesman from the Civil Aviation Authority said: "We are not aware that long-haul pilots have any higher incidences of psychotic disorders or major affective disorders than the general population."
He said it was very rare for crew to stay away for more than three days and therefore they tended to stick to a UK clock.
He said there were robust health and safety regulations in place, including fly time limitations - UK-registered pilots are prohibited from flying more than 900 hours per year.