Sleep and Chronobiological Studies in the Work Place

Studies on night work and chronobiological disorders

The Canadian Defence Department's R&D Centre and the U. S. Air Force conducted an independent study to select the optimal phototherapeutic device to improve performance in a night work adaptation program. The study, comparing the low intensity Sunnex Biotechnologies Lo-LIGHT tower with higher intensity devices, concluded, "The [Lo-LIGHT] light tower was the best device, producing melatonin suppression and circadian phase change while relatively free of side effects."

The study found that Lo-LIGHT lamps are as effective, or more effective, in shifting circadian rhythms than therapeutic that provide 20 times the light intensity (energy). The Lo-LIGHT lamps shifted body clocks (circadian rhythms) twice as much as a therapy lamp that primarily emits blue visible light [The Litebook®], even though the Lo-LIGHT tower provided only 1/20th of the light [energy]. The authors noted that "the [Lo-LIGHT] light tower achieved a numerically superior circadian phase delay in spite of the fact that it emits less than 5% of the light intensity emitted by the [Feel Bright Light©] light visor." Ref

CEMS - A U.S. Coast Guard night work adaptation program

Sunnex Biotechnologies low intensity GreenLIGHT lamps were used for the development of light management protocols of the U.S. Coast Guard's Crew Endurance Management System (CEMS). Tests were conducted at the USCG Research and Development Center to determine the usefulness of low-intensity Lo-LIGHT lamps for regulating the circadian rhythms of crews working the night shift in a program designed to improve their health and performance. Years of simulated trials were followed by years of testing on operational Coast Guard cutters and commercial vessels to evaluate the benefit of CEMS on for crews working at night.

Sunnex Biotechnologies' patented low intensity GreenLIGHT technology was found to effectively align the body clock (circadian phase) of crew members working the night shift with their work schedules on operational vessels. The light management protocol developed with Lo-LIGHT lamps was incorporated into the Coast Guard's Crew Endurance Management System (CEMS) for commercial vessels. Lo-LIGHT lamps have been installed in the wheelhouses of operating vessels to help maintain the alertness of the pilot during the midnight shift.

The ability of the Sunnex Biotechnologies' light to influence human physiology in operational vessels was presented by the USCG at the International Conference on Fatigue Management in Transportation in Seattle WA. See ref

While CEMS involves much more than regulation of circadian rhythms, including nutrition, excercise and adaptation of sleeping facilities to provide a dark and quiet environment for crews sleeping at night, adjusting the aligmenment of crewmember's circadian rhythm with their work schedule from its normal alignment with the external environment is fundamental to successful adaptation to working a night.

Night shift workers have to fight their bodies' tendency to sleep and repair itself while they are working, and then try to sleep during the day when brain is alert and the cardiovascular system is up-regulated. Aligning the internal body clock to the work schedule improves worker performance and improves the quality of sleep the following day.

Circadian re-alignment improves night shift performance, not light exposure

Low intensity GreenLIGHT has been found to improve performance for night workers in a pilot study at a commercial lumber facility. In this study, 200 lux from a GreenLIGHT lamp supplemented 130 lux of ambient white light. The GreenLIGHT lamps were used Monday through Thursday of a 5 day work week, and special eyewear was used to prevent the morning sunlight from influencing their circadian rhythms. The study found that circadian rhythms shifted, and that sleep, vigilance and performance improved to daytime levels during the latter part of the week.

It is interesting to compare the higher error rates, on Mondays and Tuesdays, when the workers were exposed to GreenLIGHT and the lower error rates on Fridays, when they were not. It would take until Wednesday for the workers circadian rhythms to align with their night work schedule, as they would re-align to the external day/night cycle over the weekend when they were engaged in regular daytime activities. It is therefore apparent that the GreenLIGHT System improves performance of night shift workers by aligning their circadian with their work schedule, and that it is not an alerting effect from the light exposure itself. The low error rates on Friday, when there was no supplemental light is further evidence of this, as avoidance of exposure to sunlight on the Friday was key to the reduced error rate on that night. The Monday and Friday results are also strong indicators that the improved performance, ie. the reduction of error rates, in the latter part of the week is not a placebo effect. Ref

NOTE: Even though the special eyewear used in the GreenLIGHT System does not impede the wearer's vision, it has been pointed out that blocking the arousing effect that morning sunlight might provide may increase the risk of an accident by workers driving home after working all night. Since this risk is generally very high for night shift workers, we strongly recommend that night shift workers using the GreenLIGHT System are provided with transportation in the mornings, and not drive themselves home.

See Using GreenLIGHT in the Work Place
Studies on Light Therapy for Depression

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