Melatonin and Light for Jet Lag: Travellers, shift workers can easily reset internal clocks

A simple, at-home treatment – a single light box and a melatonin supplement – allows travellers to avoid jet lag by resetting their circadian body clock over several days before crossing several time zones, according to new research.

Both bright light and melatonin have successfully been used in laboratory and field settings to “phase advance” (resetting the circadian clock earlier in time so that all the circadian rhythms of the body occur earlier) thereby helping people adapt to night shift work or to a new time zone following rapid transmeridian jet travel. Melatonin alone has been shown to synchronize the circadian clock of the blind to the 24-hour day.

“However, this is the first study to show that melatonin and bright light can both help to advance the circadian clock, and the combination of bright light and melatonin produces a larger phase advance than bright light alone,” said senior author Charmane Eastman, PhD.

Dr. Eastman and colleagues divided 44 healthy adults into three groups and assigned one of three treatments – placebo, 0.5 mg melatonin, or 3.0 mg melatonin, taken in the afternoon. Each participant was then evaluated at a sleep lab over a two-week period during which their waking time was adjusted forward slightly over several days.

The researchers found that those given melatonin experienced significantly larger phase advances – the 0.5 mg group at 2.5 hours and the 3.0 mg group at 2.6 hours versus the placebo group at 1.7 hours. Moreover, the participants did not experience jet lag–type symptoms. They also reported that the higher melatonin dose made the participants slightly more sleepy in the evenings after taking the pill.

The Endocrine Society & The Hormone Foundation, Nov 1, 2005