A randomized controlled trial on the effects of blue-blocking glasses compared to partial blue-blockers on sleep outcomes in the third trimester of pregnancy

Links

Summary

Spectrally engineered light boxes — both short-wavelength enriched (SW+, melanopic EDI 294 lux) and attenuated (SW-, melanopic EDI 103 lux) — improved alertness, sleep, and mood for night shift workers without compromising visual comfort. Lighting designers and healthcare facilities supporting shift workers can use these findings to tailor spectral content: low-melanopic light may support alerting while minimizing circadian disruption post-shift.

Key Findings

SW- condition (melanopic EDI 103 lux) increased on-shift alertness on the Karolinska Sleepiness Scale compared to baseline; SW+ changes were more limited.
SW+ condition (melanopic EDI 294 lux) improved both mood and sleep quality relative to baseline.
Sleep onset latency was lower and perceived performance and quality of life were higher under SW- compared to baseline.
Reported caffeine consumption was lower under SW- condition.
High satisfaction and comfort ratings were reported for both interventions (n=47, within-participants crossover design).
Psychomotor vigilance task (PVT) performance did not significantly differ across conditions.

Categories

Shift Work & Staff Wellbeing: Study directly examines lighting interventions for night shift workers, measuring alertness, sleep, and mood outcomes.

Sleep & Circadian Health: Blue-blocking glasses and spectrally engineered light boxes were evaluated for their effects on sleep onset latency and circadian-relevant light exposure.

Workplace Performance: Alertness (KSS), perceived performance, caffeine consumption, and quality of life were measured across lighting conditions in a high-security workplace.