Advancing circadian rhythms before eastward flight: a strategy to prevent or reduce jet lag.
OBJECTIVE
To develop a practical pre-eastward flight treatment to advance circadian rhythms as much as possible but not misalign them with sleep.


METHODS
One group had their sleep schedule advanced by 1 hour per day and another by 2 hours per day.


METHODS
Baseline at home, treatment in lab.


METHODS
Young healthy adults (11 men, 15 women) between the ages of 22 and 36 years.


METHODS
Three days of a gradually advancing sleep schedule (1 or 2 hours per day) plus intermittent morning bright light (one-half hour approximately 5000 lux, one-half hour of <60 lux) for 3.5 hours.


RESULTS
The dim light melatonin onset was assessed before and after the 3-day treatment. Subjects completed daily sleep logs and symptom questionnaires and wore wrist activity monitors. The dim light melatonin onset advanced more in the 2-hours-per-day group than in the 1-hour-per-day group (median phase advances of 1.9 and 1.4 hours), but the difference between the means (1.8 and 1.5 hours) was not statistically significant. By the third treatment day, circadian rhythms were misaligned relative to the sleep schedule, and subjects had difficulty falling asleep in the 2-hours-per-day group, but this was not the case in the 1-hour-per-day group. Nevertheless, the 2-hours-per-day group did slightly better on the symptom questionnaires. In general, sleep disturbance and other side effects were small.


CONCLUSIONS
A gradually advancing sleep schedule with intermittent morning bright light can be used to advance circadian rhythms before eastward flight and, thus, theoretically, prevent or reduce subsequent jet lag. Given the morning light treatment used here, advancing the sleep schedule 2 hours per day is not better than advancing it 1 hour per day because it was too fast for the advance in circadian rhythms. A diagram is provided to help the traveler plan a preflight schedule.
Eastman
Charmane I
CI
Biological Rhythms Research Laboratory, Psychology Department, Rush University Medical Center, Chicago, IL 60612, USA. ceastman@rush.edu
Gazda
Clifford J
CJ
Burgess
Helen J
HJ
Crowley
Stephanie J
SJ
Fogg
Louis F
LF
D000328:Adult; D001359:Aviation; D015992:Body Mass Index; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D020179:Jet Lag Syndrome / Q000097:blood / Q000503:physiopathology* / Q000517:prevention & control*; D008950:MMPI; D008297:Male; D008550:Melatonin / Q000097:blood; D010551:Personality; D010789:Phototherapy / Q000379:methods*; D011795:Surveys and Questionnaires
D008550:Melatonin