Submitted:
01 May 2025
Posted:
06 May 2025
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Abstract
Keywords:
1. Introduction
- Nervous system
- Circadian rhythm
2. Materials and Methods
3. Results
- Illuminance - measured in Luxes (Lx) and Foot candle (Fc).
- Wavelength – measured in nanometres (nm).
- Correlative colour temperature – measured in Kelvin (K)
3.1. Madrid Analysis


| Location | illuminance | CCT | Wavelength peaks nm |
Blue level % | ||
|---|---|---|---|---|---|---|
| Lx-Luxes | Fc-Foot candle | |||||
| 1 | Plaza Gran Vía | 134 | 12 | 2989 | 650 | 7.53 |
| 2 | GV 27 | 308 | 28 | 8489 | 470 | 28.60 |
| 3 | GV 33 | 251 | 23 | 4879 | 470 and 650 | 15.79 |
| 4 | GV 49 | 2692 | 250 | 6274 | 470 and 650 | 18.58 |
| 5 | Plaza Callao | 20 | 1 | 2294 | 650 | 0.00 |
3.1. Toledo Analysis




| Location | illuminance | CCT K |
Wavelength peaks nm |
Blue level % | ||
|---|---|---|---|---|---|---|
| Lx-Luxes | Fc-Foot candle | |||||
| 1 | Tornería street #23 | 2 | 0 | 2164 | 630 | 0 |
| 2 | Cuesta de Fernando V #9 | 10 | 0 | 3098 | 630 | 0 |
| 3 | Plaza Zocodover view to Z#6 | 9 | 0 | 3451 | 630 | 0 |
| 4 | Plaza Zocodover view to Comercio street | 17 | 1 | 2385 | 630 | 0 |
| Do you feel safer being at high intensity lighting during the night? | |
|---|---|
| No. It is enough only the necessary light for walking and facial recognition | 59.3% |
| Yes. I need high intensity lighting at night to feel safe and secure | 31.5% |
| I haven’t noticed the difference | 9.3% |

| Do you find it difficult to fall asleep after being exposed to prolonged high lighting levels? | ||
|---|---|---|
| Yes. I find it hard to fall asleep | 37% | |
| Sometimes | 35.2% | |
| Yes. I use to suffer from insomnia | 14.8% | |
| No | 11.1% | |

| At night, do you feel more comfortable with warm or cold lights? | ||
|---|---|---|
| Warm lights | 66.7% | |
| Cold lights | 16.7% | |
| I haven’t noticed. I can`t distinguish | 16.7% | |

4. Discussion
5. Conclusions
- Intensities: Use only the necessary light intensity. Avoid light intrusion and excessive bright light.
- Colour temperature: Avoid cold colour temperature at night. The colder the light, the greater tendency to secrete cortisol. Use warm colour lighting
- Avoid lighting pollution: Avoid glare and lighting upward. Light should be dimmed down or turned off when not required.
- Avoid peaks of short wavelengths (blue light).
- Avoid direct lighting emission. Consider using indirect lighting when possible. Light should address the surface, not the person.
- Consider transitions between short distances between one point to another, to let the brain to adapt to the different conditions and minimize the negative effects of ALAN in our organism.
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
| ALAN | Artificial light at night |
| CCT | Correlative colour temperature |
| Lx | Luxes (unit for lighting measurement in m²) |
| Fc | Foot candle (unit for lighting measurement in ft²) |
| GV | Gran Vía |
| nm | nanometre |
| Z | Zocodover |
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| Madrid | Location | illuminance |
CCT K |
Wavelength peaks nm |
Blue level % | |
| Lx | Fc | |||||
| 1 | Plaza Gran Vía | 134 | 12 | 2989 | 650 | 7.53 |
| 2 | GV 27 | 308 | 28 | 8489 | 470 | 28.60 |
| 3 | GV 33 | 251 | 23 | 4879 | 470 and 650 | 15.79 |
| 4 | GV 49 | 2692 | 250 | 6274 | 470 and 650 | 18.58 |
| 5 | Plaza Callao | 20 | 1 | 2294 | 650 | 0.00 |
| Toledo | Location | illuminance |
CCT K |
Wavelength peaks nm |
Blue level % | |
| Lx | Fc | |||||
| 1 | Tornería street #23 | 2 | 0 | 2164 | 630 | 0 |
| 2 | Cuesta de Fernando V #9 | 10 | 0 | 3098 | 630 | 0 |
| 3 | Plaza Z view to Z#6 | 9 | 0 | 3451 | 630 | 0 |
| 4 | Plaza Z view to Comercio st. | 17 | 1 | 2385 | 630 | 0 |
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