值夜班 伤身伤神伤脑筋

MARY LOUISE KELLY, host: We've been following the numerous reports about air traffic controllers caught sleeping on the job. Controllers often work overnight shifts or rotate among many different shifts. The Federal Aviation Administration is now changing staff scheduling practices to address fatigue among controllers.

Charles Czeisler is the director of the Division of Sleep Medicine at Harvard Medical School, and he told me why workers like air traffic controllers have a hard time adjusting to night shifts.

Dr. CHARLES CZEISLER (Harvard Medical School): People can become completely adapted to overnight work, but most do not, even if they work permanent night shifts. And the reason for that is that on their days off they typically flip back into trying to function during the daytime and sleeping at night.

KELLY: On the weekends and that type thing.

Dr. CZEISLER: Exactly. Moreover, they're living in a world in which the sun is up during the daytime and it's dark at night. And the light/dark cycle is the most powerful synchronizer of our internal biological clock. Now, it's possible to increase light intensity during nightshift work and use shorter wavelengths of light to help facilitate adaptation to working at night.

But nonetheless, most nightshift workers never fully adapt to their schedules, and hence it is more difficult for them to sustain alertness and performance when they're working at night.

KELLY: You know, it's curious, because people in all kinds of professions face sleep deprivation, many of the people working essential jobs: police, firefighters, overnight doctors and nurses in the ER(Emergency Room). Have other professions figured out a better way to do this, a better way to schedule people to work the night shift?

Dr. CZEISLER: Well, that varies by profession. Certainly, the medical profession has not done so. They currently still schedule resident physicians to work 30-hour shifts twice a week. But change comes slowly in these areas, mainly because the environment has changed dramatically over the last 50 years, requiring people to stay continuously awake in jobs that they often were able to sleep at in times gone by, but the scheduling practices have not kept pace.

In addition, we are a sleep-deprived nation. Every week, nearly two million Americans nod off or fall asleep while driving their cars on the highways. And, you know, it's part of our 24/7 culture that we think that we should be able to burn the candle at both ends(操劳过度) without suffering any consequences, and at some point, the brain seizes control and we involuntarily make the transition from wakefulness to sleep, even at very inappropriate circumstances.

KELLY: One of the things that appears to have been ruled out in trying to tackle this is naps. Transportation Secretary Ray LaHood said this week, and I'm quoting him: "On my watch, controllers will not be paid to take naps." Is that a good approach? Could naps be helpful, in your view?

Dr. CZEISLER: It's a very common approach, although it's kind of ironic. Controllers are allowed to eat while they're being paid. They are allowed to smoke cigarettes while they're being paid during a break. But they're not allowed to do the one thing that would help prepare them for work when they're on break, which would be to take a brief nap.

KELLY: And in your view, would that help?

Dr. CZEISLER: Studies done by NASA for the FAA in relationship to pilots have shown that a brief, 20-minute nap greatly increases the ability to sustain alertness during the remainder of a flight. And yet, FAA regulations do not allow pilots to nap in the cockpit(座舱). So on one out of 10 trans-Atlantic flights, the pilots are nodding off in the cockpit, but it's not scheduled or controlled in any way. It would be far better to recognize that it's going to happen, to schedule it and to ensure that it doesn't happen at unscheduled times than to simply ban it and pretend that it's going to go away.

KELLY: Charles Czeisler is director of the Division of Sleep Medicine at Harvard Medical School.

Dr. Czeisler, thanks very much.

Dr. CZEISLER: Thank you.