Jet Lag Disorder
Kathryn J. Reid
Jet lag disorder is a circadian rhythm sleep disorder (CRSD) that results from the misalignment between the internal circadian clock and the external environment when traveling across at least two times zones (1). The degree of sleep disruption and sleepiness associated with transmeridian travel is variable, depending, for example, on the number of time zones crossed, direction of travel (east or west), and age. Not all travelers experience the CRSD jet lag disorder. The functional impairment associated with jet lag disorder results from a combination of circadian misalignment and the associated sleep loss. There are several strategies for treating jet lag disorder, including directly treating the symptoms or interventions to address the cause of jet lag disorder such as speeding the adjustment of the circadian clock to the destination time zone either prior to departure or upon arrival in the new time zone.
An example of this is when one travels east from Chicago to Paris (7-hour time difference). The problem arises because of the mismatch between the clock time in the new location (Paris) and the internal circadian clock time (Chicago), as a result of the 7-hour time zone difference when it is 11 PM in Chicago it is 6 AM in Paris (see Fig. 21.1). If someone who normally goes to bed at 11 PM in Chicago tries to go to bed at 11 PM when they arrive in Paris, then according to their internal circadian clock, they will be attempting to sleep at the equivalent of 4 PM (Chicago time). As such, they will have difficulty initiating and maintaining sleep. In addition to difficulty falling asleep, if the sleep period is about 8 hours long, then according to their internal circadian clock, the wake time will be at the equivalent of 12 AM, so they are also likely to be sleepy when they wake. In this example, the circadian clock needs to phase advance by 7 hours rather than phase delay to compensate for the mismatch. It is better to phase advance because a phase delay requires shifting the internal circadian clock by 17 hours (this would be antidromic re-entrainment).
CLINICAL PRESENTATION
Individuals with jet lag disorder complain of difficulty sleeping and excessive daytime sleepiness that impairs waking function associated with transmeridian travels over at least two time zones (1).
CLASSIFICATION
EPIDEMIOLOGY/DEMOGRAPHIC OF THE DISORDERS
The prevalence of jet lag disorder is unknown. However, given the prevalence (+30 million) of international travelers departing the United States in 2009 that crossed three or more time zones the occurrence may be relatively high (3). Although this study did not directly diagnose the circadian rhythm sleep disorder jet lag, a survey study of just over 500 business travelers reported the following symptom prevalence: disturbed sleep (78%), daytime fatigue (49%), impaired mental performance (26%), gastrointestinal complaints (24%), and increased irritability (18%) (4).
DIAGNOSTIC EVALUATION
A thorough history and physical should be performed to rule out other conditions that may explain the symptoms. Polysomnography is not required unless another sleep disorder, such as sleep apnea, is suspected.
DIAGNOSIS
According to ICSD-2 criteria jet lag is associated with a complaint of insomnia or excessive daytime sleepiness following transmeridian jet travel over at least two time zones. These complaints are associated with impaired daytime function, and the sleep disturbance is not better explained by another disorder (1).
DIFFERENTIAL DIAGNOSIS
Other sleep, physical, and mental disorders should be excluded. For example, symptoms of jet lag can also include gastrointestinal complaints and may be related to an underlying medical condition. If symptoms of insomnia persist for more than 2 weeks after travel, psychophysiological insomnia may be the cause (1), particularly if poor sleep habits are perpetuating the problems.
MANAGEMENT
The primary treatment for jet lag disorder is aimed at improving sleep and waking function by speeding the adjustment of the circadian system to external and social time cues at the new destination. A summary of treatment options for both eastward and westward travel is provided in Table 21.1. It is generally recommended that realignment strategies be used only in cases where the length of stay in the new time zone is more than 48 hours (5). Adaptation can be achieved in several ways, including the use of timed exposure to or avoidance of bright-light (6,7) and/or administration of exogenous melatonin (8,9). For some travelers, minimizing symptoms immediately upon arrival is key, for others with a longer stay, a few days to adjust may be preferred. For travelers who need to arrive and perform well, preflight adjustment strategies may be the preferred option (8). These strategies also require adjustment of the sleep-wake schedule and perhaps exposure to phaseshifting agents such as light and or melatonin. Timed melatonin administration is a “standard” treatment, and timed and dosed bright light is a treatment “option” for jet lag disorder according to the practice parameters laid out by the American Academy of Sleep Medicine (10).
The key to using strategies of circadian alignment to treat jet lag disorder rely on estimating the circadian phase of the individual prior to travel. In general, the dim light melatonin onset is 2 hours prior to sleep onset, and core body temperature minimum (CBTm) is about 2 hours prior to wake. However, there is a huge amount of variability in these measures relative to sleep. Unfortunately, exposure to light or other chronobiological interventions at the wrong circadian time can worsen symptoms rather than improve them. Therefore, the timing of these interventions is crucial. Light exposure prior to the CBTm results in phase delays (shifting the clock later) of the circadian clock and light after the CBTm results in phase advances (shifting the clock earlier) (11,12). The light intensity, duration of exposure, and wavelength are also important factors that influence the degree to which the circadian clock with phase advance or delay (11, 12, 13, 14 and 15).
Exogenous melatonin can also be used to phase shift the circadian clock, but the timing of administration for phase delays and advances is different than for light (16). Melatonin can be considered a signal for darkness; therefore, melatonin given in the evening prior to the CBTm results in phase advances and when given
in the morning results in phase delays (17)
in the morning results in phase delays (17)
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