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Can Tinted Glasses Help Night Workers?
Researchers are exploring if filtered eyewear can prevent the light-induced suppression of melatonin while maintaining performance and alertness in night-shift nurses.
Some of the world’s top experts in lighting and health have been given a challenge. Establish if tinted glasses can protect the natural synthesis of melatonin in night-shift nurses while supporting their visual performance and alertness on the job.
Professor Mark Rea and Professor Mariana Figueiro of the Light and Health Research Center at the Icahn School of Medicine at Mount Sinai in New York have been awarded a grant by the Centers for Disease Control and Prevention to study personalised, non-invasive filtered eyewear interventions.
The suppression of melatonin production by nighttime retinal light exposure has been linked to health risks in nightshift workers.
Blue-blocking filters can preserve nighttime melatonin levels, and monocular light exposures can radically reduce nighttime melatonin suppression to as little as 10 per cent of that observed for conventional binocular exposures. The premise that the duo will propose is that positioning a blue-blocking orange filter over one eye will preserve binocular vision while reducing light-induced melatonin suppression relative to a completely unfiltered viewing condition.
This solution, they say, should not impede the performance of visual tasks that might require binocular vision, nor should it cause user discomfort.
Rea and Figueiro are proposing a laboratory experiment to determine whether blue-blocking filters and monocular viewing, alone or in combination, are effective for maintaining melatonin at night without affecting visual performance and subjective sleepiness.
Some tests will be conducted at the Simulation Teaching and Research Center (STAR) at the Icahn School of Medicine at Mount Sinai to determine whether altered viewing interventions could influence melatonin levels and simulated task performance requiring depth perception in healthcare workers. These could include inserting catheter or intra venous drip in a dummy.
The final trials will involve nightshift working workers operating in actual hospital environments at Mount Sinai Hospital and Memorial Hospital in South Bend, Indiana.
There they will determine whether eyewear aimed at maintaining melatonin at night would be effective, practical, and socially acceptable. The trials will employ a crossover within-subjects design, exposing subjects to six separate experimental conditions (monocular/binocular x filtered/ non-filtered, two controls) over the course of six independent sessions.
The next stage will expose the volunteers to four experimental conditions (control, filtered binocular, filtered monocular, unfiltered monocular/dominant eye occluded) over the course of four nightshifts.
The final set of tests will explore salivary melatonin levels, sleepiness scores, and Likert scale responses, as the output measures.
This proposal is significant because of its practicality. Tinted glasses could serve as inexpensive and non-invasive optical interventions which could protect night-shift workers from the natural synthesis of melatonin.
