Jet lag is not fun. Known by the medical community as desynchronosis, the condition occurs when you travel rapidly and over long distances along the Earth’s east-west axis in either direction. (It doesn’t happen if you travel along the north-south axis.) This is because your body’s circadian rhythms, your internal clock that tells you when it's day and when it's night, take a while to catch up to the new time zone.
The symptoms of jet lag include poor sleep (trouble falling asleep and/or early waking), mental fogginess, fatigue, headaches, irritability, digestion problems and reduced interest in food. If you regularly take long-distance flights, many of these symptoms will sound familiar.
But there is hope for bleary-eyed travelers, as scientists are hard at work trying to find a cure for jet lag, or at least something that will mitigate its effects. The latest advance comes from the Stanford University School of Medicine where researchers have discovered a new light-based treatment. Unlike other light exposure methods, which require sitting in front of bright lights for hours, the new discovery involves quick, bright flashes of light at night, while you sleep.
Jet lag may require a change of three time zones or more to occur. (Photo: Vinicius Depizzol/flickr)
It works because the body is more sensitive to light during the nighttime, even through closed eyelids. The flashes are enough to fool the brain into thinking it's daytime (this is a kind of “biological hack,” say the researchers) and adjust its circadian rhythms to a different time zone. With 2-millisecond flashes, which look similar to what a camera flash produces, spaced 10 seconds apart during sleep, the onset of sleepiness for study participants was delayed by close to two hours. Traditional light therapy, which uses continuous light during the daytime, achieves a delay of the onset of sleepiness of about 36 minutes.
Less is more, in this case
But why are flashes of light at night more effective than continuous light exposure during the day? There are two reasons:
“The first is that the cells in the retina that transmit the light information to the circadian system continue to fire for several minutes after the stimulus — in this case, flashing light — is no longer there,” said Jamie Zeitzer, Ph.D., assistant professor of psychiatry and behavioral sciences at Stanford School of Medicine and the senior author of the study. “The second is that the gaps of darkness between the light flashes allow the pigments in the eye that respond to the light to regenerate — that is, go from an inactive form that cannot respond to light to an active form that is able to respond to light.”
Best of all for weary travelers, the researchers have found that most people can sleep through the flashes just fine, so in theory travelers could get the benefits from this new therapy with little inconvenience.
The study was published in February in the Journal of Clinical Investigation.