quarta-feira, 1 de abril de 2015

103. What Causes Jet Lag and How to Avoid It

From VOA Learning English, this is the Health & Lifestyle Report.

Our bodies react to daylight1. In fact2, light is the most powerful environmental signal3 for re-setting4 our biological clock. Part of the job of the biological clock is to control when we sleep and when we wake5. Light has a similar effect on a common insect: the fruit fly6. So says Logan Roberts, a PhD student at the University of California, Irvine. He was the lead writer of a report on the subject7.

A long flight8 can affect one’s biological block, sometimes for days. Air travelers can get very tired9 and develop10 unpleasant feelings11 when they fly great distances across time zones12. The natural order of things can become unbalanced13 on long, overseas trips14 from east to west or from west to east.
In experiments, Logan Roberts and other researchers removed the brains15 of genetically-engineered flies16. The insects’ genes were changed for the purpose17 of this study. The researchers kept18 the brains alive in a laboratory. They used bursts19 of light to change their circadian rhythm20 by two hours.

A circadian rhythm is a 24-hour cycle, a series of events or actions that happen in the same order, over and over again21. This natural system tells our bodies when to sleep and helps to control many other processes. This internal body clock is affected by environmental signals, like sunlight and temperature. The researchers studied how the brains of the fruit flies reacted. Mr.Roberts says that by using a low-light-sensitive22 camera, they could see activity in individual neurons.

"The activity is measured by the amount23 of light these single24 neurons emit. They have a firefly gene engineered into these flies, so that25 when these cells are active, they actually26, literally light up27 in the brain and we can measure28 that activity."  The new report was published in the journal Current29 Biology. The study is the first to document in real-time how neurons react to changes in lighting like those affecting the jet-lagged traveler30.

Logan Roberts uses the word desynchronized31 when talking about the study and jet lag. This means to cause a process that takes place at times32 or in cycles independent of another process. In unscientific terms, you might say “out of sync33” or “out of whack.”34

"And we can see that some of these cells change their activity when a light is shown directly on them35. They actually become desynchronized amongst36 the groups and within37 the groups. So that sense of de-synchronization - or … when you feel out of whack with the environment38 after you experience jetlag - your nervous system actually reflects that same thing in becoming de-synchronized within itself."
In this state of de-synchronization, he adds39, communication between some neurons weakens40. He says using light to temporarily reset41 your biological clock before you travel could help to reduce symptoms42 when you arrive at your final stop. "We believe that if we can harness43 that and actually use that to actually induce this de-synchronization, this weakening of communications between these cells before jet lag, before, say, you would travel rapidly across timezones, we believe that could actually accelerate recovery44 from jet lag."

Mr. Roberts says the model used to study jet lag in fruit flies can be used in the study of other human conditions. He says that when our body clock is out of sync, we can be at greater risk for diabetes, cancer and diseases of the nervous system.

Tips45 to avoid jet lag. Light therapy is not the only treatment for jet lag. There are other things you can do to feel less tired the next time you travel. Sleep experts at the medical website WebMD have these suggestions on how to fight jet lag.

1. Try changing your meal46 and sleep times before you go. Several47 days before you travel, start moving your bedtime48 and hours for meals closer to49 the times you plan to eat and sleep on your trip.
2. Start making small changes while50 in flight. Change your watch when you get on the airplane. This is playing a trick on the mind51. But it can help you to start thinking of the time at the other end of the flight. Try to sleep on the plane if it is nighttime52 in the place where you are going.Try to stay awake53 if it is daytime.

3. Arrive early. If you are traveling for work or for a personal reason54, try to arrive a few days early, if possible. This will give your mind and body more time to correct to the new hours.
4. Drink water. Drink lots of water before, during55, and after your flight. Avoid drinking alcohol or caffeine a few hours before you plan to sleep. Alcohol and caffeine can interfere with sleep.

5. Move around56. During your flight, get up57 and walk around58 or stretch59 every so often60. But after you land61, avoid heavy exercise near bedtime. Exercise near bedtime can delay62 sleep, whether63 on an overseas trip or at home. And that’s the Health & Lifestyle Report, I’m Anna Matteo.
If you travel, what are some tips you use to make it more enjoyable?
 VOA's Rosanne Skirble researched and prepared this story. Ideas for fighting jet lag came from the medical website WebMD. Anna Matteo wrote this report for Learning English. George Grow was the editor.


  1. react to daylight = reagem à luz do dia
  2. In fact = na verdade
  3. environmental signal = sinal ambiental
  4. re-setting = reconfigurar
  5. wake = acordamos
  6. fruitfly = mosca das frutas (varejeira)
  7. subject = assunto
  8. flight = vôo
  9. get very tired = ficar muito cansado
  10. develop = desenvolver
  11. unpleasant feelings = sensações desagradáveis
  12. across time zones = ao longo de fusos horarios
  13. can become unbalanced = pode tornar-se desequilibrado
  14. overseas trips = viagens ao exterior
  15. brains = cérebros
  16. genetically-engineered flies = moscas geneticamente modificadas
  17. purpose = propósito
  18. kept = mantiveram
  19. bursts = explosões
  20. circadian rhythm20 = Ritmo circadiano = período de aproximadamente 24 horas sobre o qual se baseia o ciclo biológico de quase todos os seres vivos
  21. over and over again = várias e varias vezes
  22. low-light-sensitive = baixa sensibilidade a luz
  23. amount = quantidade
  24. single = unico(a)
  25. so that = de forma que
  26. actually = na verdade
  27. light up = acendem
  28. measure = medir
  29. Current = atual
  30. jet-lagged traveler = viajante com “jet lag” (alteração de ritmos corporais causados por viagem de alta velocidade através de vários fusos horários
  31. desynchronized = dessincronizado
  32. takes place at times = ocorre as vezes
  33. out of sync = fora de sincronia
  34. “out of whack.” = fora de sintonia
  35. shown directly on them = mostrado(a) diretamente sobre eles
  36. amongst = entre
  37. within = dentro de
  38. environment = meio ambiente
  39. adds = acrescenta
  40. weakens = enfraquece
  41. reset = reconfigurar
  42. symptoms = sintomas
  43. harness = atrelar , subordinar
  44. recovery = recuperação
  45. Tips = dicas
  46. Meal = refeição
  47. Several = vários(as)
  48. Bedtime = hora de dormer
  49. closer to = mais perto de
  50. while = enquanto
  51. playing a trick on the mind = “pregar uma peça na mente”
  52. nighttime = hora noturna
  53. stay awake = ficar acordado
  54. personal reason = razão pessoal
  55. during = durante
  56. Move around = mexa-se
  57. get up = levante-se
  58. walk around = dê uma volta
  59. stretch = alongar
  60. every so often = de vez em quando
  61. land = aterrisar
  62. delay = atrasar
  63. whether = quer (voce esteja)
  64. enjoyable = agradável