For Dr Pescatore, visual cues, such as natural sunlight, play equal importance when switching over to the local time. The worst thing to do is to immediately take a nap. Your body clock responds to light, even if it's a cloudy day. It knows it's day and knows it's ready to go,'' he said. Exposing yourself to full-spectrum light to resume normal sleep patterns is also gaining attention.
Some hotels offer rooms where bright, natural-like light comes on in place of an alarm clock.
Dr Rothenberg agreed that sunlight is the main factor for resetting your biological clock, but he said that does not mean that you should prance around in the outdoors the minute you arrive in Paris, expecting your body to immediately right itself. That would place it at noon time at your destination. He suggests wearing a pair of sunglasses from the time you get up in the morning until noon. Since your body adapts to a single time zone daily, you can take off the sunglasses an hour earlier every day, until the two times match up. The system has its limits, especially when traversing 12 time zones, and the math gets further muddled if you gradually alter your sleep patterns before your trip, but Dr Rothenberg said not to fret.