Flashing lights at night head off jet lag by resetting body clock, study finds
Light therapy fools the brain into thinking the day is longer while you get to sleep, study shows. Also in the news: poor physical fitness in middle age may be linked to smaller brain size 20 years later, and why whole grains are so good
Exposing people to short flashes of light while they’re sleeping could provide a fast and efficient method of preventing jet lag, according to a new study by researchers at the Stanford University School of Medicine. Light therapy at night is a kind of “biological hacking” that fools the brain into thinking the day is longer while you get to sleep, says the study’s senior author Jamie Zeitzer. The study involved 39 participants aged 19 to 36 years who were first put on a routine sleep-wake cycle for about two weeks. They then slept in a lab, where some were exposed to continuous light for an hour and others were exposed to a sequence of flashes of various frequencies for an hour. The study found that a sequence of 2-millisecond flashes of light, similar to a camera flash, 10 seconds apart elicited a nearly two-hour delay in the onset of sleepiness, the most efficient and fastest method of adjusting the internal clock. For participants exposed to continuous light, the delay was only 36 minutes. Zeitzer explains how flashing-light night therapy could be used to adapt to travelling from California to the US east coast, a time difference of three hours. “If you are flying to New York tomorrow, tonight you use the light therapy. If you normally wake up at 8am, you set the flashing light to go off at 5am. When you get to New York, your biological system is already in the process of shifting to east coast time. We have found that most people can sleep through the flashing light just fine.”
Couch potatoes may have smaller brains later in life
Poor physical fitness in middle age may be linked to a smaller brain size 20 years later. “We found a direct correlation in our study between poor fitness and brain volume decades later, which indicates accelerated brain ageing,” says Nicole Spartano of Boston University School of Medicine, author of the study published in the journal Neurology. For the study, 1,583 people with an average age of 40 and without dementia or heart disease, took a treadmill test. They took another one two decades later, along with MRI brain scans. During the study period, about two thirds of the participants developed heart disease or started taking beta blockers to control blood pressure or heart problems. Through the treadmill test, it was found that participants had an average estimated exercise capacity of 39 mL/kg/min, which is also known as peak VO2, or the maximum amount of oxygen the body is capable of using in one minute. For every eight units lower a person performed on the test, their brain volume two decades later was smaller, equivalent to two years of accelerated brain ageing. When the people with heart disease or those taking beta blockers were excluded, every eight units of lower physical performance was associated with reductions of brain volume equal to one year of accelerated brain ageing.
Why wholegrain foods are so good for your health
Wholegrain foods are healthy not only for their vitamins, minerals, protein and fibre, but also a particular group of health-promoting substances called benzoxazinoids, or BX for short. Scientists at Aarhus University, who first discovered BX in 2010 in certain medicinal plants and green cereals, have now discovered the substance in rye bread and other wholegrain products. The scientists conducted further investigations in rats, pigs and humans to find out if BX was absorbed by the body. “We found that the BX compounds pass through the gut wall and circulate in the body in different chemical forms. By comparing the amount that was eaten with the amount circulating in the blood and excreted in urine, we could work out that some of the substances could be transported into some of the organs where they are able to do some good,” explains lead researcher Inge S. Fomsgaard.
The scientists also found BX to have an effect on the immune system. “Eating a diet rich in BX compounds made certain immune system cells react more strongly to some types of bacteria,” says Fomsgaard. “Improving our knowledge about the function of BX can lead to the growing of crops that can be converted to food products and beverages with an optimum content and composition of these health-promoting compounds, so that consumers can increase their BX intake without having to eat large quantities of food.”