From The Ergoweb® Learning Center

Study Explores Light Therapy to Ease Night-Shift Workers

Night shifts spell chronic fatigue for most employees, a state that can compromise productivity and safety in the workplace. The use of light exposure therapy, dark sunglasses and a strict sleep schedule could be an ergonomic solution to the problem. Researchers at Rush University Medical Center say the three measures create a “compromise circadian phase position” that increases performance and alertness during night shifts while still allowing adequate nighttime sleep on days off.  

The National Sleep Foundation, a nonprofit organization dedicated to understanding sleep and sleep disorders, lists poor concentration, absenteeism, accidents, errors, injuries and fatalities among the ills associated with night shift work. The list is all the more alarming because shift workers are often employed in the most dangerous of jobs, such as firefighting, emergency medical services, law enforcement and security.

In a Rush University news release about the study, which is published in the December issue of the journal SLEEP, the researchers say theirs is the first to attempt to balance phase delaying and phase advancing light and dark exposure to achieve a specific circadian phase position that improves alertness and performance for night shift workers.
The researchers reported that when the phase delays of the experimental group had likely reached the compromise circadian position, performance for this group was close to the level during day shifts, demonstrating fast reaction times with low variability and few or no lapses. In contrast, the control group continued to show longer and more variable reaction times on all night shifts.

“The major finding of this study was that complete physiological adaptation to a night shift and day sleep schedule does not appear necessary in order to improve night shift alertness and lengthen daytime sleep,” said lead author Mark Smith in the Rush news release. “Instead, we found that partial physiological adaptation using scheduled exposure to light and darkness is sufficient to bring night shift performance back to daytime levels.” 

Previous studies have shown the effectiveness of complete adjustment to a night shift schedule for improving nighttime alertness, said Smith, a post-doctoral fellow in the Biological Rhythms Research Laboratory at the Medical Center. “But we think that most real shift workers want to be awake on their days off, and so would be unwilling to adopt a schedule that produces complete circadian adaptation because of the social constraints that are associated with it.” 

The data suggest that in addition to adopting the recommended sleep pattern and wearing sunglasses, night-shift workers who use bright light exposure therapy will be able to alter their circadian rhythm in order to improve performance during night shift work, continue daytime interaction with peers and have the ability to sleep at night on days off. 

Source: Rush University Medical Center