Bright light, melatonin timed with circadian rhythms can ease jet lag

Key takeaways:

• Strategic dosing of bright light and melatonin can “more quickly realign” circadian rhythms and mitigate jet lag.
• The longer duration of light exposure, the greater shift in circadian rhythm.

HONOLULU — The symptoms of jet lag can be mitigated through careful exposure to bright light and melatonin, according to a presentation at the CHEST Annual Meeting.

The goal of the strategy is to “more quickly realign” one’s circadian rhythms with “the new light-dark cycle and hopefully improve symptoms of jet lag,” Mariam Louis, MD, MSc, FCCP, professor of medicine at the University of Florida, said during her presentation.

Bodies naturally adjust to time zone changes at a rate of about one-and-a-half zones per day during westward travel and one zone per day going eastward, Louis said.

Trying to shift your circadian rhythms to speed up this process during a short trip will likely be more disruptive than helpful. But on a longer trip, strategically timed exposure to bright light and melatonin can be used to advance one’s circadian rhythm during eastward travel or to delay the rhythm during westward travel, lessening jet lag’s effects, she continued.

Dosage of bright light should be timed around an important point in the 24-hour sleep rhythm known as minimum core body temperature (CBT min), which occurs 2 to 3 hours before habitual wake-up. Bright light after CBT min moves the circadian rhythm earlier, and bright light before that point delays it.

“The longer the duration of exposure to light, the greater the effect will be on the phase shift,” Louis said, adding that blue light as short as 400 nm to 495 nm, as well as bright light greater than 2,500 lux, appear “to have a more significant effect on phase shift.”

Melatonin can also shift the circadian rhythm, advancing it when dosed in the late afternoon and early evening, and delaying the rhythm when taken in the morning. However, caution is warranted when prescribing melatonin for patients with epilepsy or autoimmune disease, Louis said.

She added that there are smartphone apps that can “provide tailored advice to help manage jet lag symptoms depending on where you’re going and for how long.”

Other approaches for mitigating jet lag include “common-sense” preventative measures such as hydrating, using noise-cancelling devices and avoiding caffeine and alcohol.

Louis said studies have shown stimulants help with excessive daytime sleepiness from jet lag but could come with not insignificant side effects and can be more difficult to obtain, as “jet lag is not an FDA-approved indication for stimulants.”

Louis cautioned that these measures may be helpful, but none are “completely 100% effective.”

“We clearly need a lot more research to help us better prevent jet lag symptoms, rather than just manage them,” she said.