Considerations on how to light the night-shift

Abstract

Electric lighting has decreased dependence on natural light to illuminate the workplace. Humans are genetically predisposed to be day-oriented (diurnal) and depend on daylight to regulate circadian rhythms. Shift work will force workers to sleep and work at non-biological times, inducing circadian disruption with implications for workers’ safety and health. The scientific literature may be used in practice in shift work settings to improve safety, performance and health in the workplace by reducing circadian misalignment. Alertness profiles at work and degree of melatonin suppression may indicate degree of circadian disruption among workers. However, when considering lighting solutions at night, there are several factors that need consideration. Light measures based on biological effectiveness should be used rather than room illuminance giving better predictions of performance and long-term health among workers. Also, large individual differences in light sensitivity and preferences suggest not only to rely on common lighting alone but also to implement complementary individual lighting solutions at work. Lighting advice should consider shift scheduling characteristics such as speed of turnover and shift timing to guide decisions of preferred circadian phase influence. Lighting should also include the flexibility to be fit for morning, afternoon and evening work.