Wednesday 11 December 2019

Jet-lag can be prevented by ‘hacking’ body clock with light, scientists find

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Flying high. Photo: Deposit
Flying high. Photo: Deposit
A tired passenger. Photo: Deposit

Sarah Knapton

Jet-lag can be prevented by ‘hacking’ into the body’s circadian rhythm during sleep using a flashing alarm clock, Stanford University has discovered.

Most people have suffered the sluggish feeling of trying to function in a different time-zone as the body struggles to reorientate itself to a shift in daylight.

But scientists have shown that is possible for travellers to get a head start on jet-lag before it even happens by tricking the body into thinking that dawn is breaking earlier.

Being subjected to short flashes of light while asleep speeds up the process of switching to a different time-zone before a trip, researchers have proven.

"This could be a new way of adjusting much more quickly to time changes than other methods in use today," said Dr Jamie Zeitzer, assistant professor of psychiatry and behavioural sciences at Stanford University.

Dr Zeitzer said it was a kind of "biological hacking" that fools the brain the day has started earlier.

Researchers recruited 39 participants ranging in age from 19 to 36 and synchronised their sleep routine so they were going to bed and waking up at the same time every day for about two weeks.

They then had the volunteers sleep in the lab, where half were exposed to a sequence of flashes of various frequencies for an hour.

A tired passenger. Photo: Deposit
A tired passenger. Photo: Deposit

The study found that a sequence of two-millisecond flashes of light, similar to a camera flash, 10 seconds apart elicited a nearly two-hour difference in the onset of sleepiness. The therapy effectively creates a ‘false dawn’ in the brain which more closely matches sunrise in a new country, if travelling from East to West.

Dr Zeitzer explained how the flashing-light therapy during the night could be used to adapt to travelling through a five hour time shift, such as from Britain to the Maldives, or from California to the East Coast.

"If you are flying to New York tomorrow, tonight you use the light therapy," he said. "If you normally wake up at 8 am, you set the flashing light to go off at 5 a.m.

“When you get to New York, your biological system is already in the process of shifting to East Coast time".

The body adjusts to a new time-zone by around one hour per day, so a five hour change would normally take five days to fully recover. In the meantime jet-lag can cause fatigue, lack of alertness, a general feeling of malaise and sometimes gastrointestinal problems.

The researchers said they the technology could also help shiftworkers adjust to unusual working patterns.

Dr Zeitzer added: "We have found that most people can sleep through the flashing light just fine, and that flashing-light therapy used at night could be a great method of helping to adjust the internal biological clock for all kinds of sleep cycle disruptions -- from medical residents whose sleeping schedules are constantly changing, to night-shift workers who want to be awake during daylight hours on the weekends, to sleepy truck drivers whose sleep schedules are constantly changing.

The research was published in the Journal of Clinical Investigation.

A separate study also showed for the first time why shift workers are more likely to suffer cardiovascular disease because their body clock is out of alignment.

Researchers at Brigham and Women's Hospital studied 14 people over eight days in a sleep lab, half of whom had their body clocks shifted forward by 12 hours through lighting conditions.

Results published in the Proceedings of the National Academy of Sciences showed that blood pressure rose for those people whose body clock was out of snych with natural daylight and did not dip as much as normal during sleeping hours. There was also more evidence of inflammation in the blood.

“We were able to determine, under highly controlled laboratory conditions, the independent impact of circadian misalignment on cardiovascular disease risk factors -blood pressure and inflammatory markers," said Dr Frank Scheer, neuroscientist in the Division of Sleep and Circadian Disorders at Brigham and Women's Hospital.

"Our findings provide evidence for circadian misalignment as an underlying mechanism to explain why shift work is a risk factor for elevated blood pressure, hypertension, inflammation and cardiovascular disease."

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