Background: Rapid travel over multiple time zones usually results in transient de-synchronization between environmental time and the biological clock of the individual. Common symptoms are increased daytime sleepiness, reduced sleep duration and quality, and performance impairments. Exposure to ocular bright light is known to alleviate jet lag symptoms and facilitate adaptation to a new time zone. Recently, transcranial bright light (TBL) via the ear canals has been shown to have antidepressant, anxiolytic, and psychomotor performance-enhancing effects. In this case we studied whether intermittent TBL exposure can alleviate jet lag symptoms in a randomized, double-blind, placebo-controlled study.
Methods: Intermittent light exposures (4 × 12 min; day 0: 08:00, 10:00, 12:00, 14:00; days 1-6: 10:00, 12:00, 14:00, 16:00) were administered during the 7-d post-travel period after an eastward transatlantic flight. The symptoms of jet lag were measured by the Visual Analog Scale (VAS), the Karolinska Sleepiness Scale (KSS), and the Profile of Mood States (POMS).
Results: We found a significant reduction of overall jet lag symptoms (VAS), subjective sleepiness (KSS), and the fatigue, inertia, and forgetfulness subscales of the POMS when comparing the active TBL treatment group (N = 30) to the placebo group (N = 25). For example, the normalized values of VAS in the TBL, but not the placebo, group returned to pre-travel levels by the final post-travel day (6.16 vs. 15.34).
Discussion: Results suggest a cumulative effect of TBL, as the effects emerged on post-travel days 3-4. Intermittent TBL seems to alleviate jet lag symptoms.