The newspaper said Monday about 10 percent of all passenger airline departures from U.S. airports occur at times that make it hard for pilots to get normal sleep.
Disrupting the sleep cycle can result in fatigue and has been cited as a factor in 15 airline accidents and incidents since 1993, claiming 24 lives.
"Fatigue is not something you can ever will away," Harvard Medical School sleep researcher Charles Czeisler said. "We're trying to work at a time of day when the brain wants to go asleep."
Sleep experts said interfering with normal sleep patterns makes it hard for the brain to solve problems, increasing the odds of accidents and errors.
"We operate a large number of flights when the human body has a natural drive to be asleep," said Capt. Don Wykoff of the Air Line Pilots Association.
However, a steadily declining accident rate is proof that airline schedules are safe, the Air Transport Association said.
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