It's holiday season, when many people may be whisking across time zones to visit loved ones or take a vacation. However, depending on where you go, jet lag, especially for those going east -- say from the US to Europe -- can intrude on as many as six days of vacation or business using the common guideline -- one day's adjustment for each time zone crossed. It's even more problematic for people beyond their mid-40s, when the body develops greater resistance to being on the "wrong" time. Because the circadian clock controls all body rhythms, when jet travel disrupts it, the traveler might suffer digestive upsets and irritability (both digestive and personality) in addition to being wide awake in the wee hours and sleepy at lunch. Treating with sleeping pills, as many travelers do, relieves sleep deprivation but not jet lag symptoms during the day. The only real cure for jet lag is resetting the body clock. 

Recent Learning on Resetting the Clock

Researchers at the Rush University Medical Center in Chicago have spent years studying the circadian cycle puzzle and have recently determined a method that allows travelers to avoid many of the symptoms of jet lag altogether. Their method is to reset your body clock before you set foot on the airplane. To find out more, I called Charmane Eastman, PhD, director of the Biological Rhythms Research Lab and professor of behavioral sciences at Rush, who leads this work. She explained that resetting the clock requires manipulating the two key players in the circadian cycle -- light and dark. Melatonin, the hormone associated with darkness, can also help. By shifting the timing of light and sleep, travelers can reset the clock a little each day. To move forward in time zones, as is done for most eastward travel is called phase advancing... for traveling west, it is called phase delaying. While the reset takes some time and effort, it's worth it if it ensures more enjoyment from your vacation or being more effective in your business presentation. 

Phase Advancing (for Travel West to East)

There are three key components for successful time shifting -- gradually adjusting your sleep schedule, taking melatonin at the right time and getting bright light, usually from a light box, at the right time. 

Melatonin: Taking melatonin is not like popping a sleeping pill... melatonin timing here is specifically to reset the body clock. Phase advancing requires taking 0.5 mg of melatonin about five hours before your natural fall asleep time. (Melatonin, especially in larger doses, makes some people sleepy so be careful about driving after taking it.) 

Bright light: Ideal amount of light exposure is two to three hours either in natural sunlight or with a light box pointed so your face and eyes receive the light. Getting up intermittently during that time is okay.

With that as background, you are ready to begin phase advancing for eastbound travel. The ideal would be to follow the method for the number of days equal to the number of time zones you will cross, but even fewer days will lessen your jet lag on arrival and you'll recover more quickly. Don't worry if you lie awake part of the time you are in bed, said Dr. Eastman. Simply remain in a darkened room for the duration and you will help reset your body clock. Based on a bedtime of midnight and a wakeup time of 8 am here is how to accomplish phase advancing...

• Day one: Take 0.5 mg of melatonin five hours before your usual bedtime (in other words, at 7 pm) and go to bed one hour earlier, at 11 pm. Get up one hour earlier, at 7 am and immediately begin light exposure. 

• Day two: Take the melatonin one hour earlier (6 pm), go to bed one hour earlier (10 pm) and get up one hour earlier than day one (6 am) and into the light.

• Days three, four and five: Adjust timing of bed, melatonin and light exposure to be one hour earlier than the day before. 

Phase Delaying (East to West Travel)

Westbound travel, which calls for phase delaying, is much easier for the body. The reason, said Dr. Eastman, is probably because the circadian cycle is usually longer than 24 hours, stretching to as much as 25. Phase delaying, then, is also simpler. Just set your bedtime later by an hour or two sequentially every night for at least a few days and get full light exposure for a few hours before going to bed. You don't need melatonin when phase delaying. Phase delaying is also good for eastbound travelers who are crossing seven or eight time zones -- especially for night owls. It's easier than phase advancing and, for far distances, just as beneficial. However, it is difficult to schedule if you have a job with set hours or young children. 

Depending on your direction of travel, resetting the body clock can take a lot of effort. But, when you're preparing for your once in a lifetime trip, it may be far better to have a socially awkward sleep schedule (going to bed really early or waking up really late) before you go rather than miss out on any of your time at your destination. Dr. Eastman reminded me, too, that most people don't phase shift themselves entirely into the anticipated new time zone, whether advancing or delaying. However, according to her, shifting even a few zones makes travel substantially easier and more rewarding. 

See Also

• These New Airport Lounges Are Designed to Fight Jet Lag

• How to Treat Jet Lag with Light

• Hastings MH. Physiology. A looser clock to cure jet lag. Science. 2013;342(6154):52-3.

• Song A, Severini T, Allada R. How jet lag impairs Major League Baseball performance. Proc Natl Acad Sci USA. 2017;114(6):1407-1412.

• Nicholson AN. Intercontinental air travel: the cabin atmosphere and circadian realignment. Travel Med Infect Dis. 2009;7(2):57-9.

• Reilly T, Waterhouse J, Edwards B. Some chronobiological and physiological problems associated with long-distance journeys. Travel Med Infect Dis. 2009;7(2):88-101.

• Weingarten JA, Collop NA. Air travel: effects of sleep deprivation and jet lag. Chest. 2013;144(4):1394-1401.

• Arendt J. Managing jet lag: Some of the problems and possible new solutions. Sleep Med Rev. 2009;13(4):249-56.

• Health tips for air travelers. Jet lag, cramped seats, bad air-flying can make you wish you'd never left home. Here are some suggestions for making air travel easier and perhaps a bit healthier. Harv Health Lett. 2003;28(7):3.18.

• Sun L, Peräkylä J, Kovalainen A, Ogawa KH, Karhunen PJ, Hartikainen KM. Human Brain Reacts to Transcranial Extraocular Light. PLoS ONE. 2016;11(2):e0149525.

• Sasseville A, Paquet N, Sévigny J, Hébert M. Blue blocker glasses impede the capacity of bright light to suppress melatonin production. J Pineal Res. 2006;41(1):73-8.

• Jurvelin H, Jokelainen J, Takala T. Transcranial bright light and symptoms of jet lag: a randomized, placebo-controlled trial. Aerosp Med Hum Perform. 2015;86(4):344-50.

• Jackson G. Come fly with me: jet lag and melatonin. Int J Clin Pract. 2010;64(2):135.