Canada Communicable Disease Report
Volume 29 ACS-3
1 April 2003

An Advisory Committee Statement (ACS) 
Committee to Advise on Tropical Medicine and Travel (CATMAT)*^†

TRAVEL STATEMENT ON JET LAG

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Definition

The term "jet lag" refers to a variety of physical and psychological symptoms associated with the rapid crossing of multiple time zones (meridians). These symptoms are due primarily to a disturbance of the intrinsic or endogenous circadian rhythm and sleep cycle. 

Circadian rhythms affect a wide range of biologic measures and functions, such as body temperature, blood pressure, and hormone secretion. Endogenous melatonin, secreted by the pineal gland, contributes to the physiologic regulation of circadian rhythm⁽¹⁾. Light exposure inhibits its secretion and, as a result, levels of melatonin are lowest during the day and highest at night during sleep⁽²⁾. The endogenous circadian rhythm is not usually set exactly to 24 hours but tends to be closer to 25 hours with a wide variation among individuals⁽²⁾. An individual's "endogenous clock" is usually being readjusted on a daily basis by exogenous, environmental cues (zeitgeber, German for "givers of time"). The strongest environmental cue is light⁽³⁾, but social cues and exercise are also factors. 

Symptoms of Jet Lag 

Symptoms of jet lag can include fatigue, difficulty in sleeping, and lack of concentration. Mood disturbance, anorexia, and gastrointestinal problems are also common⁽⁴⁾. Jet lag can adversely affect performance of both cognitive and manual skills, including athletic performance⁽⁵⁾. While nearly all travellers will experience some symptoms with large time zone shifts, there is considerable individual variation in both severity and recovery time. The effects are generally worse for eastward travel and with increasing age⁽⁶⁾.

In addition to disruption of the circadian rhythm, stresses related to travel, such as sleep deprivation and dehydration, can contribute to the symptoms of jet lag⁽⁷⁾. 

Recommendations for the Prevention and Management of Jet Lag 

To date, there have been few randomized, controlled trials (RCTs) of measures to prevent and manage jet lag. In the few RCTs that have been performed, there was no uniform, syndrome-specific scale with which jet lag symptoms were measured. As a result, the interpretation of these studies and comparisons among studies are difficult. 

Many of the following recommendations are not supported by RCTs or well-performed cohort studies and therefore fall into the category of grade III quality of evidence (see Table 1). Recommendations to prevent and manage jet lag can be grouped under three general headings: before travel, during travel, and after arrival in the new time zone.

Table 1.    Strength and quality of evidence summary⁽⁸⁾

Before Travel 

• Travellers crossing multiple time zones should be counselled on the likely occurrence and implications of jet lag⁽⁹⁾ (C III).

• Travellers should be encouraged to be well rested and not sleep deprived before the start of a long flight⁽⁷⁾ (C III).

During Travel 

• Travellers should try to maintain adequate hydration by drinking plenty of fluids, especially water⁽⁷⁾ (C III).

• Travellers should minimize their intake of alcohol- and caffeine-containing beverages, which can exacerbate dehydration⁽⁷⁾ (C III).

• Eating light meals may be beneficial; however, specific types of foods (e.g. carbohydrate versus protein) have been suggested but not shown to lessen the symptoms of jet lag⁽⁹⁾ (C111).

• The timing of meals may help in the adjustment to a new time zone (see recommendations below under the heading Upon Arrival)⁽⁷⁾ (C III).

• Short-acting hypnotics (sleeping pills) may be used on the flight or for the first few nights upon arrival⁽¹⁰⁾. These drugs have not been shown to have any effect on resetting the human circadian rhythm⁽¹¹⁾. Short-acting hypnotics may impair cognitive and manual skills and should be used only in consultation with a physician⁽⁷⁾ (C III).

Upon Arrival 

• The traveller who will be away from home for < 48 to 72 hours may attempt to stay on "home based" time for sleep and activity, if this is feasible⁽⁷⁾ (C III).
  

• For travel > 72 hours, the traveller should attempt immediately upon arrival to adjust his or her cycle of sleeping, eating, and activity to that appropriate to the destination⁽¹²⁾. This adjustment can be started during or even before travel, if practical⁽⁹⁾ (C III).

• If practical, travellers are well advised to avoid important activities such as business meetings or competitive sports for >= 48 hours after arrival⁽⁹⁾ (C III).

• Short-acting hypnotics (sleeping pills) may be used to facilitate sleep for the first few nights upon arrival⁽¹⁰⁾. They may impair cognitive and manual skills and should be used only in consultation with a physician⁽⁷⁾ (C III).

• Caffeine has been used as a stimulant to delay sleep upon arrival in a new time zone. The benefit of this approach for travellers, if any, is likely to be modest. Caffeine should not be consumed for several hours before travellers try to fall asleep⁽⁹⁾ (C III).

• If practical, travellers may consider spending time outside during the day at their destination, to help with adjustment to the new time zone. Adequate studies using light manipulation in travellers have not been done⁽⁷⁾ (C III).
  

Melatonin 

In recent years there has been a great deal of interest in the possible role of exogenous melatonin in the management of jet lag. As noted previously, endogenous melatonin, secreted by the pineal gland, contributes to the physiologic regulation of circadian rhythm⁽¹⁾. 

Only a small number of randomized, double-blind studies have examined different regimens of melatonin for the treatment of jet lag, and the results of these studies have been inconsistent^(13-15). The conflicting data may be partially explained by the lack of a uniform, syndrome-specific scale to measure jet lag severity.

• The effect of melatonin on the prevention or modulation of jet lag, if any, is likely to be small and this drug cannot be recommended for these purposes at this time⁽¹⁶⁾ (C 1).

• Well-designed studies with sufficient power are needed to clarify melatonin's potential role in the management of jet lag.

Melatonin is not licensed in Canada, and its safety has not been established. Melatonin is sold as a dietary supplement in health food stores in the United States. The FDA (Food and Drug Administration) does not regulate dietary supplements, and therefore the purity and potency of melatonin products obtained in the U.S. cannot be guaranteed. 

References 

1. Minors DS, Waterhouse JM. Circadian rhythms in general. Occup Med 1990;5:165-82. 

2. Disorders of chronobiology. In: Kryger MH, Roth T, Dement WC (eds). Principles and practice of sleep medicine. 3^rd ed. Philadelphia: WB Saunders, 2000:589-614. 

3. Czeisler CA, Kronauer RE, Allan JS et al. Bright light induction of strong (type 0) resetting of the human circadian pacemaker. Science 1989;244:1328-33. 

4. Moore-Ede MC. Jet lag, shift work, and maladaption. News Physiol Sci 1986;1:156-60. 

5. Comperatore CA, Krueger GP. Circadian rhythm desynchronosis, jet lag, shift lag, and coping strategies. Occup Med 1990;5:323-41. 

6. Monk TH, Buysse DJ, Reynolds CF et al. Inducing jet lag in older people: adjusting to a 6-hour phase advance in routine. Exp Gerontol 1993;28:119-33. 

7. Tasman A. Psychiatry. 1^st ed. WB Saunders Company, 1997:1233-34. 

8. MacPherson DW. Evidence-based medicine. CCDR 1994;20:145-47.
    

9. Committee to Advise on Tropical Medicine and Travel. Travel statement on jet lag. CCDR 1995;21:148-51. 

10. WHO. International travel and health. Geneva: WHO, 2002 

11. Turek FW, Van Reeth O. Use of benzodiazepines to manipulate the circadian clock regulating behavioural and endocrine rhythm. Horm Res 1989;31:59-65. 

12. Rakel RE. Conn's current therapy 2002. 54^th ed. W.B. Saunders, 2002:155 

13. Petrie K, Dawson AG, Thompson L et al. A double-blind trial of melatonin as a treatment for jet lag in international cabin crew. Biol Psychiatry 1993;33:526-30. 

14. Spitzer RL, Terman M, Williams JBW et al. Jet lag: clinical features, validation of a new syndrome-specific scale, and lack of response to melatonin in a randomized, double-blind trial. Am J Psychiatry 1999;156:1392-96. 

15. Caldwell JL. The use of melatonin: an information paper. Aviat Space Environ Med 2000;71:238-44. 

16. Goroll AH. Primary care medicine. 4^th ed. Lippincott Williams & Wilkins, 2000:1192

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