Circadian phase delay induced by phototherapeutic devices.
BACKGROUND
The Canadian Forces has initiated a multiple study project to optimize circadian phase changes using appropriately timed phototherapy and/or ingestion of melatonin for those personnel on long-range deployments and shift workers. The work reported here compared four phototherapeutic devices for efficacy in effecting circadian phase delays.


METHODS
In a partially counterbalanced treatment order, 14 subjects (7 men and 7 women), ages 18-51 yr, participated in 5 weekly experimental sessions of phototherapy with 4 different phototherapy devices (light tower, light visor, Litebook, LED spectacles) and a no-phototherapy control. Phototherapy was applied from 24:00 to 02:00 on night. (1) Dim light melatonin onset (DLMO) was assessed on night 1 and night. (2) Subjects were tested for psychomotor performance (serial reaction time, logical reasoning, and serial subtraction tasks) and completed the Stanford Sleepiness Scale on night 1 at 19:00, 23:00, 01:00, 02:00, and 03:00. After phototherapy, subjects completed a phototherapy side-effects questionnaire.


RESULTS
All phototherapy devices produced melatonin suppression and significant phase delays. Sleepiness was significantly decreased with the light tower, the light visor, and the Litebook. Task performance was only slightly improved with phototherapy. The LED spectacles and light visor caused greater subjective performance impairment, more difficulty viewing the computer monitor and reading printed text than the light tower or the Litebook. The light visor, the Litebook, and the LED spectacles caused more eye discomfort than the light tower.


CONCLUSIONS
The light tower was the best device, producing melatonin suppression and circadian phase change while relatively free of side effects.
Paul
Michel A
MA
DRDC Toronto, Toronto, Ontario, Canada. mpaul@drdc-rddc.gc.ca
Miller
James C
JC
Gray
Gary
G
Buick
Fred
F
Blazeski
Sofi
S
Arendt
Josephine
J
D000293:Adolescent; D000328:Adult; D000337:Aerospace Medicine; D000704:Analysis of Variance; D021081:Chronobiology Disorders / Q000628:therapy*; D005221:Fatigue / Q000517:prevention & control; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000032:analysis*; D008875:Middle Aged; D010789:Phototherapy / Q000295:instrumentation*; D011597:Psychomotor Performance; D012463:Saliva / Q000737:chemistry; D011795:Surveys and Questionnaires; D014851:Wakefulness
D008550:Melatonin