A six-hour flight from Boston to London can cause worse jet lag than flying nearly the same distance from Boston to Los Angeles, according to sleep expert Charles Czeisler, PhD, MD, chief of the Division of Sleep Medicine and Circadian Disorders at Brigham and Women’s Hospital (BWH).
“Going east, you get morning light at midnight your old time, so you’re getting light exposure for many hours before your normal wake time,” Czeisler told The Boston Globe. “It’s more difficult to go to sleep earlier than you usually do, rather than later.”
Czeisler says each time zone crossed going east adds another day before the body adjusts to local time, while westbound travel takes half as many recovery days.