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 around^56. 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.

Vocabulary

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