Exposure to brief flashes of light while sleeping the night before a trip may help travelers adjust more easily to time zone changes and avoid jet lag, findings of a new study revealed.
Jet lag does not just cause inconvenience to many travelers. It is also linked to a range of health problems. Now, a new technique shows promise in preventing jet lag and problems with the body's biological clock.
In an experiment led by Jamie Zeitzer, a former postdoctoral scholar from Stanford University School of Medicine and is now affiliated with the Singapore Eye Research Institute, researchers asked 39 participants who were between 19 and 36 years old to adopt a regular sleep-wake cycle for a two-week period.
The volunteers were then asked to sleep in the lab where they were exposed to either continuous light for an hour and a sequence of flashing light for the same length of time.
Current light-therapy treatments for people with sleep disturbances involve sitting in front of bright lights during the day as this allows the circadian clock to gradually transition to a new time zone before a trip.
An earlier study conducted by Zeitzer and colleagues though suggests that light therapy is most effective at night because the body's circadian rhythm that controls sleep cycle is more sensitive to light at night. Their new study, however, found that this night-time light therapy is more effective when short flashes of light are used instead of continuous light.
For their experiment, which was published in the Journal of Clinical Investigation on Feb. 8, Zeitzer's team found that those who were exposed to light flashes experienced nearly two hours delay in the onset of sleepiness, the most efficient and fastest way of adjusting the body's internal clock. Those who were exposed to continuous light, on the other hand, had a delay of only 36 minutes.
Zeitzer cited an example of how the flashing-light therapy can impact people who travel from California to the East Coast.
"If you are flying to New York tomorrow, tonight you use the light therapy. If you normally wake up at 8 a.m., you set the flashing light to go off at 5 a.m," Zetizer explained. "When you get to New York, your biological system is already in the process of shifting to East Coast time."
The researcher said that the technique can also help other individuals who need help adjusting their internal biological clocks such as medical residents, night-shift workers and truck drivers.
These individuals face increased health risks due to their work schedule. Frequent disruption of the circadian clock has been shown to increased risks for cancer, diabetes and obesity.
Another benefit of using the flashing-light therapy to prevent jet lag is that it can change the circadian timing during sleep without causing interferences.
"At peak ISI, flashes were at least 2-fold more effective in phase delaying the circadian system as compared with exposure to equiluminous continuous light 3,800 times the duration," the researchers wrote in their study. "Flashes did not change melatonin concentrations or alertness in an ISI-dependent manner."
