Phase advance with separate and combined melatonin and light treatment.
BACKGROUND
Melatonin and light treatment are recommended for hastening adaptation to time zone change. We evaluated an afternoon regimen of 3 mg sustained release (SR) melatonin with and without next morning green light treatment for circadian phase advance. Effects of melatonin and light were tested separately and then combined to determine if the total phase change is additive or synergistic.


METHODS
For each condition (melatonin, placebo, light, melatonin plus light), 11 subjects spent from Tuesday evening until Friday afternoon in the laboratory. For all four conditions, the following sleep schedule was maintained: night 1, 2345 to 0630 hours, night 2, 1600 to 0530 hours, and night 3, 2345 to 0700 hours. For the light-only condition, light treatment was administered between 0700 and 0800 hours on Thursday. For melatonin-only or placebo conditions, capsules were administered at 1600 hours on Wednesday. For the combined condition, melatonin was administered at 1600 hours on Wednesday with light treatment between 0600 and 0700 hours on Thursday. Circadian phase was assessed by calculating dim light melatonin onset (DLMO) from salivary melatonin, using a mean baseline +2 standard deviations (BL+2 SD) threshold. For all four conditions, pre-treatment and post-treatment DLMO assessments were on Tuesday and Thursday evenings, respectively.


RESULTS
Phase advances were: melatonin at 1600 hours, 0.72 h p<0.005, light treatment from 0700 to 0800 hours, 0.31 h, non-significant, and the combined treatment, 1.04 h p<0.0002.


CONCLUSIONS
The phase advance from the combination of afternoon melatonin with next morning light is additive.
Defence Research & Development Canada, 1133 Sheppard Ave. West, P.O. Box 2000, Toronto, ON, Canada. michel.paul@drdc-rddc.gc.ca
Michel A
MA
Paul
Gary W
GW
Gray
Harris R
HR
Lieberman
Ryan J
RJ
Love
James C
JC
Miller
Matthew
M
Trouborst
Josephine
J
Arendt
D056044:Actigraphy; D000222:Adaptation, Physiological; D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D001683:Biological Clocks / Q000187:drug effects / Q000528:radiation effects; D002214:Capsules; D002940:Circadian Rhythm / Q000187:drug effects / Q000528:radiation effects; D003131:Combined Modality Therapy; D003692:Delayed-Action Preparations; D004311:Double-Blind Method; D006801:Humans; D020179:Jet Lag Syndrome / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage* / Q000378:metabolism; D008875:Middle Aged; D009864:Ontario; D010789:Phototherapy; D012463:Saliva / Q000378:metabolism; D012890:Sleep / Q000187:drug effects / Q000528:radiation effects; D013997:Time Factors; D014195:Travel
D002214:Capsules; D003692:Delayed-Action Preparations; D008550:Melatonin