Key Takeaway
Workers exposed to blue-enriched light during the day reported better alertness, mood, and nighttime sleep quality compared to standard white light.
Summary
This randomized controlled trial examined the effects of blue-enriched white light exposure during work hours on alertness, performance, and sleep. Office workers were exposed to either blue-enriched (17,000K) or standard white (4,000K) light for 4 weeks each.
During the blue-enriched light condition, workers reported significantly improved alertness, positive mood, reduced fatigue, and better concentration. Crucially, they also reported improved sleep quality at night, demonstrating that daytime light exposure affects nighttime sleep.
This study provides RCT evidence that light exposure during the day - particularly blue-enriched light similar to morning sunlight - improves both daytime function and nighttime sleep.
Methods
- Randomized crossover design
- 4 weeks each condition
- Blue-enriched vs standard white light
- Measured alertness, mood, performance, sleep quality
Key Results
- Improved subjective alertness
- Better mood and reduced fatigue
- Enhanced concentration
- Improved nighttime sleep quality
Limitations
- Self-reported outcomes
- Workplace setting only
- May not generalize to morning sunlight