Tired of feeling, well, tired after a long flight? A team of researchers from the Stanford University School of Medicine believe they have found a solution to jet lag, via a process that involves exposing sufferers to short flashes of light. If it works, the new tactic could not only help people adjust to time zone changes, but could also be employed to help anyone dealing with a disrupted sleep cycle.
Experts have long believed that exposure to precisely-tuned bright lights for long lengths of time is useful for combating the effects of jet lag, which is the result of a circadian rhythm disruption (all that time zone hopping spins the hands around). But in their new study, the Stanford team suggests that quick bursts of light, rather than a continuous stream, has a better effect on those whose circadian rhythms are thrown out of whack.
For the study, a group of 39 participants, ranging in ages 19 to 36, were asked to follow a routine sleep-wake cycle, going to bed and rising at the same time every day for two weeks. Afterward, they spent the night sleeping in a lab. There, some were exposed to an hour of continuous light; others, meanwhile, were exposed to an hour of strategic series of flashes.
These flashes — similar to those from a camera — were each 2-milliseconds long and occurred 10 seconds apart.
The next day, researchers found that those who had been exposed to the short flashes of light had experienced a two-hour delay in the occurrence of melatonin (based on saliva samples) the following evening. What that means, essentially, is that, opposed to the continuous stream of light, the flash therapy caused a shift in their melatonin production. This is crucial for getting their rhythms back on track.
But why do the flashing lights work so much better than continuous light?
“There are pigments (chemicals) in the eye that absorb light and cause cells in the eye to have an electric response, which is then transmitted to the circadian clock in the brain,” Jaime Zeitzer, author of the study and assistant professor of psychiatry at Stanford, explained in an email. “Once light hits these pigments, it takes time for them to convert from an inactive state that cannot respond to light to an active state that can again respond to light.”
This is a process he referred to as dark adaptation. Zeitzer compared it to the experience of going to a pitch black movie theater, and how much brighter everything seems upon leaving.
“It is not just perceptually brighter,” says Zeitzer. “Your eye has dark-adapted and your brain is actually receiving more light.”
And as for why light therapy needs to occur when the person is snoozing, Zeitzer explains it is because the circadian clock is generally most sensitive to light when people are asleep. Therefore, to get the largest changes in circadian timing, the light needs to be delivered when the person is resting. That, or someone needs to be awake when they would normally be sleeping.
The results are promising, but Zeitzer admits that he and the team have some more ground to cover.
“We still have many areas that we need to optimize to improve the flashes,” he says. “We selected two-millisecond flashes, but that was a bit random and we will be testing everything from microsecond flashes to seconds-length flashes.”
Zeitzer says he will also be studying how long the flashes should be given out, as well as their color and which cells in the eye are responding directly to the light.
When perfected, this therapy could be extremely helpful to not only to international travelers, but also shift workers and even astronauts — really, anyone who has circadian rhythm issues. Let's hope it moves forward quickly: a prescription of flashing light far surpasses a bottle of pills any day.