Circadian-Informed Lighting Boosts Sleep Quality for Night Shift Workers

Summary: Research out of Flinders University has found that circadian-informed lighting, designed to align with the body’s natural rhythms, improves sleep quality and work performance for night shift workers. The study, conducted in a tightly controlled laboratory setting, tested lighting interventions to simulate the challenging environments faced by shift workers, such as those on submarines. Results showed that strategic exposure to circadian lighting accelerated body-clock adjustments, improved alertness, and increased sleep duration compared to traditional lighting setups. The findings, published in SLEEP, suggest that such lighting interventions could improve the health and well-being of shift workers in various industries.

Key Takeaways:

Circadian-Informed Lighting Boosts Performance: The study found that exposure to circadian-informed lighting led to fewer mistakes during work tasks and improved alertness in night shift workers.
Faster Body-Clock Adjustment: Circadian lighting shifted participants’ body clocks about one hour faster per day compared to traditional lighting, helping them adapt more quickly to night shifts.
Improved Sleep Quality: Participants exposed to circadian-informed lighting achieved almost one additional hour of sleep and reported feeling less sleepy during their shifts.

The use of circadian-informed lighting, where artificial lighting is synchronized to the natural biological rhythms or a person’s “body clock,” significantly improves quality of sleep and work performance for night shift workers, a new trial has found.

The Flinders University trial is among the first tightly controlled in-laboratory studies to have simultaneously evaluated circadian-lighting effects on markers of body-clock timing, work-shift cognitive performance, and sleep following an abrupt transition to night shift work.

The results of the trial have produced two papers published in SLEEP, finding that strategic exposure to light accelerated body-clock adjustment and improved alertness and performance, as well as sleep after a night shift.

Understanding Circadian Rhythms and Shift Work Disruptions

“Circadian rhythms reflect our body’s internal clocks that control the activity and timing of bodily functions, including our sleep-wake cycle,” says Flinders University sleep researcher Hannah Scott, PhD, author of Circadian-informed lighting improves vigilance, sleep, and subjective sleepiness during simulated night shift work, in a release. “Shift work causes circadian disruption, for which well-timed light exposure, designed to promote alertness and facilitate circadian adjustment, is one of the most potent methods to help retime the body clock.”

In Australia, around 15-16% of Australian workers report being shift workers. For both men and women, rotating shifts with varying schedules each week are the most prevalent type of shift work.

Supported by the Defence Science and Technology Group through the Research Network for Undersea Decision Superiority, the findings will be of particular interest for shift workers in enclosed environments such as submarines where lighting is typically dim, according to researchers.

Challenges of Shift Work in Submarine Environments

“Given the complete lack of normal day-night lighting, shift work on submarines may be particularly challenging for the body clock to adjust to,” says Scott in a release. “We wanted to explore the unique challenges posed by night shifts, particularly the disruption to sleep-wake schedules, which can lead to impaired mental and physical performance, poorer sleep, and health issues.

“We found that the use of circadian-informed lighting promoted better-improved job performance and sleep for those working irregular hours.”

Nineteen adults participated in the study, which took place in FHMRI Sleep Health’s laboratory under tightly controlled conditions that simulated night work environments. Participants were exposed to two different lighting scenarios for a period of eight days to compare how their body clock adjusted and how they performed in a series of tasks.

Circadian Lighting’s Impact on Body-Clock Adjustment

The circadian-informed lighting consisted of blue-enriched and dim, blue-depleted conditions designed to help the body clock adjust to night work, whilst the traditional dim, blue-depleted lighting simulated the standard lighting conditions onboard submarines.

The research team then assessed key circadian measures including melatonin levels and core body temperature, along with other outcomes including cognitive performance and sleep.

Importantly, over four consecutive simulated night shifts, the circadian-informed lighting shifted participants’ body clocks around one hour faster per day compared to the standard lighting.

Key Findings and Implications for Night Shift Workers

Alisha Guyett, lead author of A circadian-informed lighting intervention accelerates circadian adjustment to a night work schedule in a submarine lighting environment, says that the findings are very promising for night shift employers and employees.

“The overarching benefits of circadian-informed lighting on sleep and alertness are very clear from this study. Our findings suggest that strategic lighting interventions can likely be used to enhance the performance, sleep, safety, and well-being of night shift workers exposed to inadequate light during their work shift,” says Guyett in a release. “The circadian-informed lighting interventions significantly accelerated participants’ adjustment to night work, which could have important implications for improving the health and performance of those who regularly work night shifts.”

Notably, after circadian-informed lighting, participants achieved almost one hour more of sleep compared to the standard lighting condition as well as reporting lower levels of sleepiness during their shifts.

To test alertness, participants in both lighting conditions were subjected to the Psychomotor Vigilance Task test, a behavioral attention measure. Those in circadian-informed lighting conditions made half as many (7.4 lapses) mistakes as those in standard lighting (15.6 lapses).

Optimizing Lighting in Various Work Environments

“This study highlights the importance of the circadian system and circadian-friendly lighting to help alleviate some of the significant challenges of shift work,” says Senior Flinders Health and Medical Research Institute: Sleep Health researcher Peter Catcheside, PhD, in a release. “It adds to what we already know about the use of these interventions to help optimize workspaces for enhanced performance, safety, and well-being in the modern workforce.

“These findings have important implications for submariner lighting conditions, but also mining and other workplace environments where lighting conditions may make it more difficult for shift workers to successfully adjust their body clocks to the work schedule,” he adds.