Circadian‑Informed Lighting Improves Vigilance and Sleep in Simulated Night Shifts
Summary
This randomized, counterbalanced crossover lab study (19 adults) tested “circadian-informed” lighting—blue-enriched light during night work and blue-depleted light when appropriate—against a dim, blue-depleted control during four simulated night shifts with daytime sleep. Under the circadian-informed condition, participants showed about 50% fewer psychomotor vigilance (PVT) lapses by the end of the protocol, reported lower sleepiness (KSS) at mid-shift on days 6–7, and slept ~52 minutes longer during daytime sleep by day 7. Effects on other cognitive tasks were inconsistent. Overall, aligning light spectrum and intensity with circadian biology improved vigilance, reduced sleepiness, and increased daytime sleep in this simulated night-shift setting.
Why It Matters For Night Shift Workers and Night Owls
Light isn’t just ambience—it’s a biological signal. In this study, using brighter, blue-enriched light while working nights and warmer, blue-depleted light before sleep led to fewer attention lapses, less mid-shift sleepiness, and longer daytime sleep by the end of the week. If you work nights, a practical takeaway is to opt for cooler, brighter light during your shift, then dim and warm your lighting (and limit screens) in the hours before sleep. This can help your brain stay alert on shift and make daytime sleep deeper and longer—though not every type of performance will improve equally. Field trials in real workplaces are the next step, but this lab evidence is a strong signal that smart lighting can meaningfully help.
Notes
Lab simulation informs real‑world specs.