Alerting Effect of Light: A Review of Daytime Studies

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Summary

This systematic review of 20 studies (1991–2022) found that only 7 confirmed a measurable alerting effect of light during daytime, highlighting the difficulty of translating lab findings into practical office lighting recommendations. The authors conclude that more research using ecologically valid, polychromatic light conditions at office-appropriate intensities is needed before definitive lighting design guidelines can be established.

Key Findings

Of 142 studies retrieved, only 26 investigated daytime alerting effects of light; 20 met inclusion criteria.
Only 7 out of 20 reviewed studies found a statistically significant alerting effect measured via self-assessment or cognitive performance enhancement.
No consistent trend in lighting conditions (intensity, spectrum, duration) that reliably produced alerting effects was identified across studies.
Both polychromatic and monochromatic light sources were examined, but conditions used in most studies were not directly transferable to realistic office environments.