Jet-lag plans timing light and melatonin never had a controlled test
The day-by-day schedules for light, darkness and melatonin come from laboratory studies of the body clock, not from controlled tests on travellers.
What the study found
Light-and-melatonin jet-lag schedules never had a controlled trial
Today's advice times light, darkness and melatonin to move the body clock before and after a flight, worked out in laboratory studies of the clock. No controlled trial has tested that combination on a real trip. The schedules are reasoned from physiology, not yet shown to work.
The caveat · Parts tested alone, not together
Pieces have been tried alone: non-drug fixes after real flights mostly failed, with 9 of 13 controlled studies finding no change in one review. Three days of earlier bedtimes with morning light moved the clock 1.5 to 2.1 hours in the laboratory, with no flight afterwards. Six mountain bikers combined all three before flying to Tokyo, with no comparison group.