Jet lag and shift work sleep disorders: How to help reset the internal clock

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Bright light at work, sunglasses on the way home

Various field studies have described hastening of circadian adaptation (and immediate alerting effects) during night shifts with the use of bright light.20

Boivin and James47 found that workers who received 6 hours of intermittent bright light during their shifts experienced significantly greater phase delays than those who received no such intervention. Those receiving bright light also wore sunglasses during the commute home (to protect from an undesired phase advance), and this has demonstrated favorable effects as an independent intervention.48

Drug treatment of shift work sleep disorder

Melatonin: Mixed results. Two field studies found that taking melatonin (5–6 mg) before the daytime sleep period had a favorable impact on subjective sleep quality.49,50 However, two other studies found no such benefit with doses ranging from 6 to 10 mg.51,52 Differences between these studies—eg, shift schedules, dosages, and the time the melatonin was taken—preclude definitive comparisons.

Effects of melatonin on workplace alertness are indeterminate because of inconsistent measurements of this variable. Importantly, a simulated shift work study found no phase-shifting advantages of melatonin in those who concomitantly used bright light during their work shift with or without morning protective eyewear.48

Hypnotic drugs. In simulation studies and field studies, people taking benzodiazepine receptor agonists have consistently said they sleep better.53–58 A simulation study noted additional benefit in the ability to stay alert during the night shift (assessed by maintenance of wakefulness testing),55 but two other studies saw no changes in manifest sleepiness (assessed with multiple sleep latency tests).53,54 These divergent findings may represent different effects on these two dimensions of sleepiness.

The only field study to assess post-sleep psychomotor performance found no impairments after taking 7.5 mg of zopiclone, a relatively long-acting nonbenzodiazepine hypnotic.57

Stimulants. In the largest trial to date of shift work sleep disorder, modafinil 200 mg (the only drug currently FDA-approved for shift work sleep disorder) had significant benefits compared with placebo with respect to objective measurements of workplace sleepiness, reaction time performance testing, and self-rated improvement of symptoms.59 Perhaps because of the low dose studied, both treated and untreated patients continued to manifest sleepiness within the pathologic range on objective testing.

Although the efficacy of caffeine is well documented as a countermeasure for sleepiness during experimentally induced sleep deprivation,20 very few field trials have specifically addressed impairments associated with shift work sleep disorder. In one study, caffeine at a dose of 4 mg/kg taken 30 minutes before starting a night shift provided objective improvement in both performance and alertness.60

Strategic napping is an additional practical intervention to promote alertness during night shifts, and cumulative data indicate that it provides objective and subjective improvements in alertness and performance.61,62 Earlier timed naps (ie, before or during the early portion of a shift) of short duration (ie, 20 minutes or less) are likely to produce maximal benefit, because they avoid sleep inertia (the grogginess or sleepiness that may follow a long nap), and also because they have no effect on the subsequent daytime sleep bout.61,63

Interventions may also be used in combination. For example, napping in conjunction with caffeine results in a greater degree of increased objective alertness than either intervention alone.60

How about days off?

The recommendations described here presume that shift workers maintain the workday sleep-wake schedule continuously, including when they are not at work. This is likely not a real-world scenario.

Smith et al64 developed a “compromise” phase position, whereby internal rhythms are optimized to facilitate alertness during work and sleepiness during the day, while allowing one to adopt a non-workday sleep schedule that maintains accessibility to family and social activities. In brief, non-workday sleep starts about 5.5 hours earlier than workday sleep; all sleep bouts are followed by brief exposure to bright light (to avoid excessive phase delay); and, as described previously, both workplace bright light and protection from morning light are implemented.

Although further studies are needed to determine whether this regimen is practical in real life, study participants who achieved desired partial phase shifts had performance ratings on a par with baseline levels, and comparable to those in a group that achieved complete re-entrainment.64

Finally, all shift workers need to be encouraged to protect the daytime bedroom environment just as daytime workers protect their nighttime environment. Sleep should be sought in an appropriately darkened and quiet environment, phones and doorbells silenced, and appointments scheduled accordingly.

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