Avoid food, beat jet lag23rd May 2008
Our brains have a second clock which keeps track of mealtimes, separately from the mechanisms which are sensitive to day and night.
Researchers at Harvard University in the United States say this means that adjusting meal times could be an important tool in recovery from jet lag.
Based on experiments with mice, the brain is thought to have a "feeding clock" which keeps track of feeding times. When food is scarce, the clock keeps the brain awake until food is found.
The report, published in the journal Science, suggests that shift workers and travellers can fend off tiredness by not eating.
The brain's master clock is found in a region called the suprachiasmatic nucleus, and governs daily sleep cycles, behaviour and metabolism.
The insight would not make the symptoms of jet lag disappear entirely, but could make them much more manageable, according to the research team.
For example, someone travelling from the US to Japan is forced to adjust to an 11-hour time difference, which takes about a week for most people, because the body's master clock can only shift a small amount each day.
A period of fasting lasting about 16 hours would be enough to reengage the clock in the new time zone, the team suggested.
The body's rhythms are highly sensitive to disruption, and disturbed patterns found in shift workers and international travellers have been linked to insomnia, depression, heart disease, cancer and neurodegenerative disorders.
Until now, they were thought to be governed primarily by sensitivity to daylight.
The Harvard team led by Clifford Saper studied mice which were missing a key clock gene, Bmal1. By restoring this gene to different parts of the brain, one at a time, they were able to pinpoint the "feeding clock" to an area of the hypothalamus known as the dorsomedial nucleus.
The mice were also observed to stay awake until they had eaten, suggesting that the feeding clock could override the circadian master clock.
Saper advised travellers to avoid any food on the plane, and then to eat as soon as they land, which should help avoid some of the uncomfortable feelings of jet lag.
Sleep expert Neil Stanley at Norwich University Hospital said the discovery could be very useful to people who fly a lot and who work unsociable hours.
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