Adjusting meal times can help travellers recover from jet lag, a study
suggests.
Harvard University researchers believe the brain has a second "feeding clock"
which keeps track of meal-times, rather than daytime, after studying mice.
When food is scarce, the feeding clock overrides the master clock, keeping
animals awake until they find food.
Thus, shift workers and travellers can keep tiredness at bay by not eating,
they suggest in the journal Science.
Our daily sleep cycles, behaviour and metabolism are governed by a powerful
master clock, which resides in an area of the brain known as the
suprachiasmatic nucleus.
It's never going to make the symptoms of jet lag disappear entirely, but it
could certainly make them a lot more manageable
Dr Neil Stanley, of Norwich University Hospital
Disruption of these "circadian" rhythms have been shown to be linked with
insomnia, depression, heart disease, cancer and neurodegenerative disorders.
This "circadian" clock is highly sensitive to daylight. But scientists have for
several years been aware of a second "feeding" clock which is sensitive to our
eating patterns.
To understand the relationship between the two clocks, a Harvard team 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.
What is more, by observing the mice's behaviour, they found that the "feeding
clock" could supersede the circadian master clock, keeping the mice awake until
they had the opportunity to eat.
Beneficial
Lead researcher Clifford Saper suggested travellers and shift workers may be
able to use the feeding clock to adapt to changes in time zones and night-time
schedules which leave them feeling groggy and jet-lagged.
"If, for example, you are travelling from the US to Japan, you are forced to
adjust to an 11-hour time difference.
"Because the body's biological clock can only shift a small amount each day, it
takes the average person about a week to adjust to the new time zone.
"And, by then, it's often time to turn around and come home.
"A period of fasting with no food at all for about 16 hours is enough to engage
this new clock.
"So, in this case, simply avoiding any food on the plane, and then eating as
soon as you land, should help you to adjust and avoid some of the uncomfortable
feelings of jet lag."
Dr Neil Stanley, a sleep expert at Norwich University Hospital, said the
discovery was "potentially very beneficial" to travellers and people who work
unsociable hours.
"It's never going to make the symptoms disappear entirely, but it could
certainly make them a lot more manageable," he said.