Traveling across several times zones can cause an individual to experience jet lag, including trouble sleeping at night and thus difficulty remaining awake during the day. These effects largely reflect de-synchronization between the body's internal time clock and local environmental cues.
The program, which seeks to re-synchronize the body with its new environment, considers inputs like background light level and the number of time zones traveled. Then, based on a mathematical model, the program gives users exact times of the day when they should apply countermeasures such as bright light to intervene and reduce the effects of jet lag.
Timed light exposure is a well known synchronization method, and when used properly, this intervention can reset an individual's internal clock to align with local time. The result is more efficient sleep, a decrease in fatigue, and an increase in cognitive performance. Poorly timed light exposure can prolong the re-synchronization process.
Using their computational method, researchers simulated shifting sleep-wake schedules and the subsequent light interventions for realigning internal clocks with local time. They found that the mathematical computation resulted in quicker design of schedules and also predictions of substantial performance improvements. They were able to show that the computation provided the optimal result for timing light exposure to reduce jet lag symptoms.
"Using this computation in a prototyped software application allows a user to set a background light level and the number of time zones traveled to obtain a recommendation of when to expose a subject to bright light, such as the bright lights sometimes used to treat Seasonal Affective Disorder" said lead-author Dennis Dean. "Although this method is not yet available to the public, it has direct implications for designing schedules for jet lag, shift-work, and extreme environments, such as in space, undersea or in polar regions."
"This work shows how interventions can cut the number of days needed to adjust to a new time zone by half," said co-author Daniel Forger.
The next phase of this research includes the addition of interventions such as naps, caffeine and melatonin to help the process of realigning the internal body clock while reducing decreased performance experienced during travel across time zones.
To learn more about why sleep matters, the science behind it and how to improve your sleep, visit http://healthysleep.med.harvard.edu/.
FINANCIAL DISCLOSURE: The work described in this article was supported by US AFOSR F49620-95-1-0388 and F49620-95-1-0388, NASA Cooperative Agreement NCC 9 with NSBRI HPF-00405, NIH M01-RR02635 and NIH R01-NS36590. EBK is also supported by NIH K02-HD045459. DBF is an AFOSR Young investigator. DAD is also supported by T32 HL07901-10. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
COMPETING INTERESTS: The authors have declared that no competing interests exist.
CITATION: Dean DA II, Forger DB, Klerman EB (2009) Taking the Lag out of Jet Lag through Model-Based Schedule Design. PLoS Comput Biol 5(6): e1000418. doi:10.1371/journal.pcbi.1000418