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 Table of Contents 
REVIEW ARTICLE
Year : 2018  |  Volume : 7  |  Issue : 3  |  Page : 507-510  

Jet lag: Heuristics and therapeutics


1 Department of Internal Medicine, Maimonides Medical Center, New York City, NY, USA
2 Department of Dental Sciences, King George Medical University, Lucknow, Uttar Pradesh, India
3 Department of Critical Care Medicine, Maimonides Medical Center, New York City, NY, USA

Date of Web Publication17-Jul-2018

Correspondence Address:
Dr. Paurush Ambesh
Department of Internal Medicine, Maimonides Medical Center, New York City, NY
USA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jfmpc.jfmpc_220_17

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  Abstract 


Jet lag is one of those common medical problems, to which most people don't give a serious thought. However, it is intricately intertwined with our normal circadian rhythm. It is classified as a sleep disorder. There is also a dearth of good scientific literature, not to mention clinical trials on the subject. Slowly but steadily, the scientific community is realizing the various deleterious health effects of jet lag and is devising innovative methods to counter them. This narrative review touches upon the etiopathogenesis, clinical manifestations and therapeutic strategies effective against the nagging problem of jet lag.

Keywords: Circadian rhythm, insomnia, jet lag


How to cite this article:
Ambesh P, Shetty V, Ambesh S, Gupta SS, Kamholz S, Wolf L. Jet lag: Heuristics and therapeutics. J Family Med Prim Care 2018;7:507-10

How to cite this URL:
Ambesh P, Shetty V, Ambesh S, Gupta SS, Kamholz S, Wolf L. Jet lag: Heuristics and therapeutics. J Family Med Prim Care [serial online] 2018 [cited 2019 Jul 15];7:507-10. Available from: http://www.jfmpc.com/text.asp?2018/7/3/507/236847




  Introduction Top


Jet lag, often deemed as a trivial inconvenience, is actually a recognized sleep disorder.[1] Despite its limited duration, jet lag can produce deleterious health effects in high functioning individuals. Most people who have experienced an overseas flight have experienced jet lag and its deleterious effect on sleep. It occurs because of disruption of the circadian rhythm due to rapid transition across time zones, resulting in asynchrony between the local time and the human circadian clock (which is normally regulated by the solar light–dark cycle). Internal signals for wakefulness and sleep are thrown in disarray due to mismatch with the local light–dark cycle.


  The Normal Human Circadian Rhythm Top


The human circadian rhythm is intimately intertwined with the sleep-wake cycle and is affected by melatonin secretion and changes in the core body temperature (CBT).

During a normal circadian phase, dim light causes melatonin to increase approximately 2 h before habitual sleep onset. This physiological response is known as dim light melatonin onset. A concurrent decrease in CBT results in reduced levels of alertness, which in turn creates a strong propensity for sleep (at night). At dawn, melatonin levels drop and become undetectable. The CBT rises thereby accentuating the circadian alerting signal. This has the overall effect of promoting wakefulness. For approximately 16 h during daytime, the circadian alerting signal counters the increasing homeostatic sleep drive.[2]

Natural bright light is the most potent modifier of the circadian cycle. However, after a change in the light–dark cycle due to air travel, phase shifts do not occur instantaneously. These phase shifts may take many days to adjust to the new time zone. As a result, the internal circadian clock is still set to the original time of travel onset. Interestingly, the amount of dyssynchrony is dependent on the number of time zones traversed. Jet lag manifests as daytime sleepiness, mood changes, gastrointestinal discomfort, psychomotor retardation, and insomnia [Figure 1].
Figure 1: Common symptoms of jet lag

Click here to view


Generalized fatigue and malaise are common manifestations.[3] These symptoms may be due to prolonged immobility, dehydration, and variable meal times which may or may not be related to the phenomenon of time zone transition. The problem of malaise can be resolved with proper sleep and diet, but until the circadian rhythm realigns, the jet lag persists. Symptoms of jet lag can become chronic in frequent travelers, for example, flight crew and international executives.


  Diagnosing Jet Lag Top


Jet lag is a clinical diagnosis. The International Classification of Sleep Disorders, Third Edition, lists the following criteria for diagnosis:[4]

  • Excessive daytime sleepiness or distortion of sleep cycle along with decreased total sleep time that coincides with jet travel across at least two time zones (east to west or west to east)
  • Generalized fatigue or presence of somatic symptoms occurring within 2 days of travel onset
  • No other disorder or condition can be attributed for the sleep disturbance.


Jet lag is often mistaken for travel fatigue. The travel fatigue syndrome involves generalized fatigue, occasional headache, and mental weariness as a result of distorted sleep routine. This occurs due to stress of travel. An important distinction is that travel fatigue does not depend on number of time zones traversed. It can occur after northbound or southbound travel. Restful sleep generally abolishes the symptoms of travel fatigue.[3]

In the absence of specific treatment, the natural circadian rhythm adjusts to the destination time by approximately 1 time zone/day for eastbound travel and 1.5 time zones/day for westbound travel.[5]


  Factors That Produce Jet Lag Top


Travel direction – Since the inherent body clock cycle exceeds 24 h, it is much more convenient to lengthen the day than to shorten it. Thus, it is easier to travel westward than eastward.

A recent study has found eastward travel to have more deleterious effect on sleep than westward travel.

Subjective fatigue and overall motivation were also found to be reduced. Results were more pronounced for travel time <3 days.[6]

Number of time zones traversed: The greater the number of time zones traveled, the greater the circadian disarray. Another factor which increases fatigue is the duration of travel.

In another recent study, a direct correlation was seen between subjective ratings of jet lag and distance traveled during flight. Rather sleep and subjective responses were decreased as a result of change in environment.[7]

Lost sleep time during travel: Overnight travel causes the most sleep loss, but it may be reduced if the passenger is seated in first class (with the fully reclining option). Jet lag symptoms, however, will not abate until the circadian clock is resynchronized at the destination.

Idiosyncratic tolerability: Tolerance to circadian phase misalignment varies among individuals and decreases with age. Local light exposure: For realignment of the circadian clock, local light exposure is very important. It is affected by arbitrary factors such as activity level and work schedule of the passenger.


  Evidence-Based Therapeutics to Counter Jet Lag Top


Resetting the circadian clock

As the circadian rhythm slowly synchronizes with the local time zone, symptoms of jet lag gradually wane. It has been postulated that the circadian clock resets an average of 57 min earlier after eastward travel and 92 min later after westward travel.[5] A study corroborated these findings using melatonin secretion timing as a marker of circadian timing.[8] The circadian clock is slightly longer than 24 h. The process of resynchronization can be sped up by utilizing naturally existing clock-resetting mechanisms to compensate for minor differences between the 24-h solar time and the natural body clock.

Role of light exposure

It is believed that the timing of light exposure is a vital cue for circadian rhythm realignment. This phenomenon is prevalent in most animals as well as humans. To compensate for any deviation from a 24-h cycle, morning light exposure moves the clock to an earlier time while evening light exposure moves it to a later time.[9] At night, the separation between phase delays (evening response) and phase advance (morning response) diminishes. Since people normally sleep in darkness with closed eyes, sleep timing by itself does not resynchronize the rhythm. Sleep halts exposure to light temporarily, thereby assisting in circadian clock modulation.

When the individual's flight lands at a time zone destination, the timing and intensity of light is critical to clock realignment. Local factors such as season, weather, and activity level of the traveler also contribute to determining the rate of synchronization. Intentional exposure to bright light at local day times may expedite the process.

It is recommended to seek bright light exposure in the evening after westbound journey and in the morning after eastbound journey. This may be useful when the individual has traversed as many as eight time zones of travel. Avoiding bright light exposure may be helpful in circumstances where eight or more time zones have been crossed so that light which was previously experienced as “morning” is now experienced as “evening”. The reverse is true as well. Thus, it is also recommended to avoid 1st h of daylight after an eastward journey and 1st h of evening after a westward journey [Figure 2].[10],[11]
Figure 2: Recommended light exposure for respective travel direction

Click here to view


Avoidance of light can be discontinued after few days, at the point when the circadian rhythm will have readjusted. Some studies show that an alternative to direct avoidance of bright light is the use of sunglasses.[12] More research needs to be done in the field of light avoidance before conclusive guidelines can be established.

The duration of jetlag symptoms may also depend on direction of travel.[10]

It may be more pronounced in travelers with pretravel-inverted circadian rhythms, for example, night shift workers or a traveler on a prolonged eastbound flight.[13] This is because clock advancement is harder than clock delaying. Thus, some experts recommend that any flight that traverses more than eight time zones should be regarded as westward.[3]

Melatonin – the darkness signal

Melatonin is secreted for about 10 h each night in tandem with the light–dark cycle. It is a darkness signal, with effects which antagonize those of light exposure. If melatonin is taken in the morning, it resets the circadian clock to a later time, and if taken in the evening, it resets it to an earlier time.

At higher doses, it may act as a hypnotic. Studies have shown a significant benefit of melatonin in reducing symptoms of jet lag.[14],[15],[16] With a usual dose of 5 mg, no major adverse effects have been reported.

Customizing the sleep cycle

Another approach is to attempt the same sleep–wake home routine upon arrival at the destination.[17] Often, it is not possible due to social or business obligations. Studies involving simulated conditions of long-distance international air travel in hyperbaric chambers have been done. Fowler et al. found that decreasing travel-induced sleep disruption might lessen travel fatigue. However, any improvements in recovery of physical performance were not observed.[18]

Role of stimulants

Caffeine intake might combat jet lag-induced daytime sleepiness. In one study involving passengers traveling eastward, slow-release caffeine (300 mg) enhanced alertness.[19] However, the downside of caffeine use is the potential exacerbation of jet lag-induced insomnia. In one study, Armodafinil demonstrated improvement in wakefulness after flight travel across six time zones.[20] Modafinil, a similar drug, may have similar beneficial effects and is being evaluated in ongoing trials.

Role of sedative drugs

A short course of sedatives has been shown in randomized trials to alleviate insomnia arising from jet lag.[21],[22],[23],[24],[25]

One randomized, placebo-controlled trial demonstrated that the use of zolpidem (10 mg q.h.s) for 3–4 nights after traveling eastward (over more than 5 time zones) significantly improved sleep time and quality.[26]

For overnight flights, short-duration hypnotic agents (3–4 h) may be particularly useful.

The potential side effects of hypnotics include confusion and amnesia.[27]

Global amnesia was seen in many individuals taking triazolam during flight travel.[28] A test dose at home, a few days before travel, may help obviate this problem.

Hypnotics may also increase immobility, thereby accentuating the risk of deep vein thrombosis during flight travel.[29]


  Conclusion Top


Jet lag is a common and underdiagnosed medical problem that can have varying effects on motor and cognitive performance. With international travel becoming increasingly common among professionals, jet lag warrants significant medical attention. Few treatment strategies exist to counter the deleterious effects of jet lag on the normal circadian cycle. More research trials need to be performed in order to establish concrete treatment recommendations.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Waterhouse J, Reilly T, Atkinson G, Edwards B. Jet lag: Trends and coping strategies. Lancet 2007;369:1117-29.  Back to cited text no. 3
    
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American Academy of Sleep Medicine. International Classification of Sleep Disorders. 3rd ed. Darien, IL: American Academy of Sleep Medicine; 2014.  Back to cited text no. 4
    
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Fowler PM, Knez W, Crowcroft S, Mendham AE, Miller J, Sargent C, et al. Greater effect of East versus West travel on jet lag, sleep, and team sport performance. Med Sci Sports Exerc 2017;49:2548-61.  Back to cited text no. 6
    
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Thornton HR, Miller J, Taylor L, Sargent C, Lastella M, Fowler PM, et al. Impact of short- compared to long-haul international travel on the sleep and wellbeing of national wheelchair basketball athletes. J Sports Sci 2017;3:1-9.  Back to cited text no. 7
    
8.
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Khalsa SB, Jewett ME, Cajochen C, Czeisler CA. A phase response curve to single bright light pulses in human subjects. J Physiol 2003;549:945-52.  Back to cited text no. 9
    
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Eastman CI, Burgess HJ. How to travel the world without jet lag. Sleep Med Clin 2009;4:241-55.  Back to cited text no. 11
    
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Smith MR, Cullnan EE, Eastman CI. Shaping the light/dark pattern for circadian adaptation to night shift work. Physiol Behav 2008;95:449-56.  Back to cited text no. 12
    
13.
Takahashi T, Sasaki M, Itoh H, Yamadera W, Ozone M, Obuchi K, et al. Melatonin alleviates jet lag symptoms caused by an 11-hour eastward flight. Psychiatry Clin Neurosci 2002;56:301-2.  Back to cited text no. 13
    
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15.
Arendt J, Aldhous M. Further evaluation of the treatment of jet lag by melatonin: A double blind crossover study. Ann Rev Chronopharmacol 1988;5:53-5.  Back to cited text no. 15
    
16.
Claustrat B, Brun J, David M, Sassolas G, Chazot G. Melatonin and jet lag: Confirmatory result using a simplified protocol. Biol Psychiatry 1992;32:705-11.  Back to cited text no. 16
    
17.
Lowden A, Akerstedt T. Retaining home-base sleep hours to prevent jet lag in connection with a westward flight across nine time zones. Chronobiol Int 1998;15:365-76.  Back to cited text no. 17
    
18.
Fowler PM, Duffield R, Morrow I, Roach G, Vaile J. Effects of sleep hygiene and artificial bright light interventions on recovery from simulated international air travel. Eur J Appl Physiol 2015;115:541-53.  Back to cited text no. 18
    
19.
Beaumont M, Batéjat D, Piérard C, Van Beers P, Denis JB, Coste O, et al. Caffeine or melatonin effects on sleep and sleepiness after rapid Eastward transmeridian travel. J Appl Physiol (1985) 2004;96:50-8.  Back to cited text no. 19
    
20.
Bogan R, Rosenberg R, Tiller J, Yang R, Youakim JM, Earl CQ, et al. R-modafinil for excessive sleepiness associated with jet lag disorder. Presented at the 23rd Annual Meeting of the Associated Professional Sleep Societies. Seattle; 6-11, June, 2009.  Back to cited text no. 20
    
21.
Suhner A, Schlagenhauf P, Höfer I, Johnson R, Tschopp A, Steffen R, et al. Effectiveness and tolerability of melatonin and zolpidem for the alleviation of jet lag. Aviat Space Environ Med 2001;72:638-46.  Back to cited text no. 21
    
22.
Buxton OM, Copinschi G, Van Onderbergen A, Karrison TG, Van Cauter E. A benzodiazepine hypnotic facilitates adaptation of circadian rhythms and sleep-wake homeostasis to an eight hour delay shift simulating westward jet lag. Sleep 2000;23:915-27.  Back to cited text no. 22
    
23.
Reilly T, Atkinson G, Budgett R. Effect of low-dose temazepam on physiological variables and performance tests following a westerly flight across five time zones. Int J Sports Med 2001;22:166-74.  Back to cited text no. 23
    
24.
Lavie P. Effects of midazolam on sleep disturbances associated with westward and eastward flights: Evidence for directional effects. Psychopharmacology (Berl) 1990;101:250-4.  Back to cited text no. 24
    
25.
Daurat A, Benoit O, Buguet A. Effects of zopiclone on the rest/activity rhythm after a westward flight across five time zones. Psychopharmacology (Berl) 2000;149:241-5.  Back to cited text no. 25
    
26.
Jamieson AO, Zammit GK, Rosenberg RS, Davis JR, Walsh JK. Zolpidem reduces the sleep disturbance of jet lag. Sleep Med 2001;2:423-30.  Back to cited text no. 26
    
27.
Dolder CR, Nelson MH. Hypnosedative-induced complex behaviours: Incidence, mechanisms and management. CNS Drugs 2008;22:1021-36.  Back to cited text no. 27
    
28.
Morris HH 3rd, Estes ML. Traveler's amnesia. Transient global amnesia secondary to triazolam. JAMA 1987;258:945-6.  Back to cited text no. 28
    
29.
Silverman D, Gendreau M. Medical issues associated with commercial flights. Lancet 2009;373:2067-77.  Back to cited text no. 29
    


    Figures

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