Occupational Health and Safety With Lighting

Occupational Health and Safety With Lighting

The objective of this work is to examine the use of lighting in managing some of the adverse effects of shift work and to discuss and demonstrate the ability to critically evaluate and use information on a relevant subject.

Shift work has been demonstrated in scientific research to negatively affect the health of workers and even been noted to be a factor in women developing breast cancer. Shift work is a factor in many cases of depression and other health complications and diseases as well. The eye of the human being is sensitive to light in a variation of ranges based upon the wavelength of the light. Light-measurement considers the sensitivity curve of the eye, or the 'photonic response cycle' using the measurement-unit known as a 'lux'. Some light in this sensitivity range is brighter than other light. The following chart demonstrates that bright light of a yellow light than that of a deep blue light "even though their actual output may be the same.' (2001)

Photopic Response Curve

Source: Litebook: What Makes 'the Litebook' Unique?

Occupational health and safety hazards are presented when workers are not alert while working due to fatigue associated with disruption in their body's circadian rhythm and certainly the night shift worker is affected moreover the affect upon the shift worker is much more severe. In specific jobs the responsibility and liability of workers requires that employers take extra steps in assuring that their workers are fully alert and miss no details. One example is the pediatric nurse and another is the over-the-road truck driver. In both cases, it is critical that the worker do not fall asleep, work while fatigued, or miss minute details, which costs lives or injuries to themselves and others while working.


The work of Ben Harder (2006) published in the Science Daily online entitled: "Bright Lights, Big Cancer: Melatonin-Depleted Blood Spurs Tumor Growth" states that Richard G. Stevens, employed in 1987 at Pacific Northwest Laboratories in Richland, Washington notified Walter Willett at Harvard Medical School in Boston that he believed that "nighttime illumination, by interrupting the body's mainly nocturnal production of the hormone melatonin, might increase the risk of breast cancer." (Harder, 2006) This is because "a woman's blood provides better sustenance for breast cancer just after she's been exposed to bright light than when she's been in steady darkness." (Harder, 2006) Russel J. Reiter, neuroendrocrinologist at the University of Health Science Center in San Antonio states: 'Sleep per se is not important for melatonin...but darkness is." (Harder, 2006)

Harder (2006) states: "Melatonin forms in the pineal gland, located in the brain, and circulates in the bloodstream. Blood concentrations of the hormone rise after dark from low daytime values and usually peak in the middle of the night. Because the pineal gland responds to signals transmitted by the optic nerves, bombarding a person's eyes with bright light during the night can erase the usual nocturnal surge and lower the overall melatonin production for the day. That observation concerned researchers, in part because melatonin has slowed breast cancer growth in lab experiments." (Harder, 2006) Reported as well is the fact that unusually low breast cancer rates exist among blind women who have melatonin concentrations that are higher than average. The work of Schernhammer, a study of nurses conducted by Harvard states findings that "shift workers have an elevated risk of breast cancer." (Harder, 2006) the work of Whitehead (1999) entitled: "Optimal Scheduling Strategies for Emergency Medicine" states that exposure to bright light results in a shift in the nadir temperature "changing the plasma cortisol concentration pattern..." And promotes alertness while improving cognition while working.

The work entitled: 'Exposure to Bright Light and Dark to Treat Physio Maladaptation to Night Work" provides information concerning the physio-maladaptation that occurs among shift workers stating that it is a "misalignment in the sleep-wake cycle and the output of the hypothalamic pacemaker that regulates the circadian rhythms of certain physiological and behavioral variables." (Czeisler, et al., 1990) This study provides clinical proof that the functioning of the circadian pacemaker that on the "sixth consecutive night of sedentary work in ordinary light the mean nadir of the endogenous temperature cycle continued to occur during the night, indicating a lack of circadian adaptation to the nighttime work schedule." (Czeisler, 1990) the difference in the subjects in the study exposed to bright light at night and "to nearly complete darkness during the day, and the temperature nadir shifted after four days of treatment to a significantly later, midafternoon hour" indicated that the subjects had adapted successfully to the changes in the regulation of their circadian rhythm.

The work of Monk (1986) entitled: "Advantages and Disadvantages of Rapidly Rotating Shift Schedules: A Circadian Viewpoint" distinguished the sick feeling experienced by the individual when they are working different shift into two unique categories which are those of:

Circadian Disharmony: The "jet lag" malaise one experiences until adaptation to a new shift occurs, which may last as long as a week; and Inappropriate Phasing: Trying to stay awake or to sleep when the circadian clock says otherwise, as occurs with isolated night shifts. (Monk, 1986; as cited in Whitehead, 1999)

Sunnex Biotechnologies developed 'The Greenlight System', which is stated to be successful in the counteraction of night work fatigue in the work place. The work entitled, "Light Management for Night Shift Adaptation" relates that fatigue is acknowledge as a "...major problem in work places requiring night work. Maintaining alertness at night is crucial in environments where impaired judgment can put safety at risk. Working at night also adversely affects the health and well being of worker's internal body clock with their activities." (Sunnex Biotechnologies, 2001)


Sunnex Biotechnologies Greenlight System uses a low-intensity narrow spectrum technology presently under a patent. According to Sunnex Biotechnologies, "...white light is often used in research trials to demonstrate the benefits of aligning circadian rhythms with night work schedules these studies have determined that intensities between 5,000 and 10,000 lux of white light are most successful in effectively shifting the human body clock to align it with a night work schedule." (Sunnex Biotechnologies, 2001) the problem is that the white light, due to its high intensity, is not practical in the work place. Furthermore, the white light is believed to be harmful to the human eye. Furthermore, moderate light in the range of 1,000 to 2,000 lux has been found to be ineffective. The Greenlight System of Sunnex Biotechnologies uses a light that is low intensity, under 300 lux, and that "shifts human circadian rhythms to an equivalent extent as does 5,000-10, of white light." (2001) Greenlight technology is reported to be used by the U.S. Coast Guard's CEMS program in countering fatigue. In fact, the low intensity Greenlight Technology System underwent testing for effectiveness in suppression of "...melatonin and shifting circadian rhythms to align the internal body clock of night workers with their work schedule." (Sunnex Biotechnologies, 2001)

The Greenlight Technology system is a non-UV source of light that works in filtering light. Blue rays, the most harmful of all lights in the white light spectrum among all visible light forms are specifically those needing to be filtered because they cause: "...oxidative damage in the retina and contributing to the development of age related blindness." (All ages, may use this system safety and ocular condition has no effect on the usefulness of this Greenlight system offered by Sunnex Biotechnologies. This lighting technology comes in several forms and offers exposure to an entire room along with GLS Eyewear, which may be integrated into the Greenlight System specifically for workers who are exposed to the bright morning sun following their shift. The following is a list of Sunnex Greenlight models along with descriptions and prices of each model:

WH 120 Wheelhouse unit - includes guide and baffles (1 lamp unit) $600.00

WH 215 Wheelhouse unit - includes light guide and baffles $100.00

MT 120 Room Lighting (1-lamp unit) $700.00

MT 220 Room Lighting (2-lamp unit) $800.00

WE 100 Sunnex Biotechnologies Eyewear $200.00

The above-stated prices do not include either shipping or installation charges. This company rents Greenlight System equipment as well. This system offers safety for workers both on and off the job. The system works to keep workers on a sleeping-schedule. The system works through a process of regulation of bright light exposure of workers and is able to do so on and off the job. Greenlight may be used both in the work place and by workers after their shift in the form of Greenlight GLS Eyewear, which enables workers to work off a night shift and continue normal activities without bright light penetrating their eyes so they are ready to sleep when it is time for them to sleep. This system makes the workplace safer through enabling shift workers to sleep and arrive at work rested instead of fatigued and presenting possible occupational safety hazards in the work place.