For anyone who has been unfortunate enough to be stuck looking up at the ceiling of their bedroom or hotel trying to sleep. But have been unable even though it maybe 3.30 in the morning. Will know that crossing time zones (jetlag) & shift work is a nightmare.
But a new drug that has been successfully tested in human volunteers may offer hope for future travellers and shift-workers.
In two clinical trials the drug tasimelteon, which helps to shift the natural ebb and flow of the body's sleep hormone, melatonin, increased the time volunteers spent asleep, helped them to get to sleep quicker and reduced the amount of time they spent awake during the night.
The research team did not test how well their subjects performed the day after taking the drug - something that would be crucial on a business trip - but it should help travellers to feel more normal.
"All the evidence suggests it would because if you have shifted your clock and you've slept well, then you should perform well the next day," said Dr Elizabeth Klerman, at Brigham and Women's hospital, Boston, who led the study.
Melatonin is released naturally by the pineal gland deep in the brain in response to light levels. It binds to receptors in the brain's circadian clock and acts to entrain the clock to the day-night cycle. "You can think of melatonin as something which quiets the awakening signal from your body clock," said Klerman. "It does not put you to sleep ... but once you drop off it prevents you from waking up early if you are trying to sleep at an unusual time."
Tasimelteon mimics melatonin and binds to the same receptors. Klerman and her colleagues conducted two clinical trials in which they studied volunteers who had their body clock advanced by five hours - the same as travelling from New York to London.
They compared sleep patterns in people given the drug and those given a placebo. Neither the researchers nor the subjects knew who had been given which.
The researchers report today in the Lancet that in the larger of the trials, volunteers on the medium dose of the drug slept for an average of 48 minutes longer. The time they spent awake during the night was also less: 140 minutes on average for the placebo group, compared with 106 minutes for people who took a medium dose of tasimelteon. The study was funded by Vanda Pharmaceuticals, which makes the drug, though it has not yet been approved by the Federal Drug Administration.
Klerman said although melatonin is available in US health food stores - it is not legal in the UK - there is conflicting evidence about how well it works. It is licensed as a supplement and does not fall under the remit of the FDA. "What you get in a health food store isn't necessarily pure and the dose isn't necessarily what they say on the bottle," she said.
To combat jet lag, the NHS recommends topping up on sleep before you travel; adjusting to your destination, by shifting your watch as soon as you get on the plane; avoiding alcohol; and by spending lots of time outdoors in the daylight. If you are considering taking melatonin supplements the NHS recommends consulting your doctor first.