More zzz’s thanks to new shades!

More than 13 million North Americans are shift workers. And those who work the ‘graveyard shift’ are thought to be at an increased risk of breast and colon cancer, heart disease, depression and anxiety disorders, and obesity because of repeated disruptions to their biological clock due to exposure to light at night.

Lunenfeld senior investigator Dr. Robert Casper and doctoral candidate Shadab Rahman wanted to find out if these disruptions could be prevented.

“This has turned out to be one of our most exciting and rewarding research projects,” said Dr Casper. “There is tremendous potential to improve the quality of life for shift workers and to prevent mistakes and accidents in hospitals and factories.”

Since most of the adverse health affects of exposure to light at night are caused by a narrow range of wavelengths corresponding to the blue range of the visual spectrum, Casper and Rahman tested a theory that blocking out the blue range would prevent the disruptions in biological rhythms. The internal body ‘clock’ regulates the timing of various biological processes including the secretion of hormones such as melatonin (which slows cancer growth) and cortisol (a stress hormone) and maintains these important body functions on a 24-hour cycle also known as circadian rhythms.

The researchers tested their glasses on 13 participants who wore them under simulated night time shift work conditions. Using the glasses prevented hormone disruptions and improved alertness, performance and mood during simulated shift work.

Further studies are planned to measure the quality and duration of sleep of night shift nurses - on their nights off. Field studies are also being done with support from the Canadian Auto Workers Union to see if the glasses will be beneficial in night shift factory workers.

“The optical filters we have developed could be used as eyewear by shift workers or could be applied to light covers or to the surface of light bulbs in situations where wearing glasses or goggles would be difficult,” said Rahman. “The potential benefits are far reaching, including jet-lag and sleep disorders in adolescents.”

The researchers have produced a prototype of the glasses that will be available to the public starting February 2009 online at www.zircadium.com.