The approach of summer calls up thoughts of travel to distant lands, but the first few days in Paris can be miserable as your body clock tries to sync up with local time. To lessen the effects of jet lag, it’s important to get daylight working in your favor, which is not as simple as many in-flight magazines make it sound.
Eastbound travelers often get this advice: go out in the sunlight immediately upon arrival. In some cases, this will work to your advantage, but in others, it will make your jet lag worse. It all depends on when the exposure to light in the new time zone occurs in relation to your body temperature. Here’s how it works.
Your body temperature is lowest from one to three hours before you normally get up. So if you get up at 7 a.m., your body temperature bottoms out around 5. This temperature minimum is a critical meridian when it comes to determining the effect light will have on your sleep. The simple rule to remember is this: exposure to bright light soon after your temperature minimum will help you fall asleep sooner at night. Exposure to bright light in the hours leading up to the temperature minimum is going to delay your sleep cycle, making it harder to get to sleep.
Taking an Overnight Flight to Europe
Let’s say you live in the eastern part of the U.S. and you decide to take an overnight flight to Paris, arriving at 8 a.m. To get in sync with local time, your body clock will need to shift forward six hours so you’re ready to go to sleep six hours sooner.
Yet if you heed the advice offered by in-flight magazines and spend the first few hours of your trip outdoors in the sun, your body clock will shift in the wrong direction. At the time of your 8 a.m. arrival, your body thinks it’s 2 a.m.—well before your temperature minimum. Rather than helping you fall asleep sooner that first night in Paris, exposure to morning sunlight is going to delay your sleep cycle further, making it harder yet to adjust to life in the Latin Quarter.
So what to do if, after an eastbound flight, you arrive at your destination before your body temperature reaches its low point? If spending the first few hours of your trip indoors in low lighting is unappealing (and why wouldn’t it be? We’re talking Montmartre and the Luxembourg Gardens, for Pete’s sake!), then definitely wear dark glasses for your maiden stroll down the Champs-Elysées.
On the other hand, if your arrival time falls after your body temperature reaches its nadir, immediate exposure to sunlight is the best way to lessen jet leg and start your trip on the right foot.