Impact of lighting on physical securityChuck McCormick
Ever feel anxious on some parking lots at night and not know why? You maybe being influenced by the color spectrum of the light the fixture/bulb are producing.
Light, it is both naturally occurring and manufactured that stimulates sight and makes things visible . A more technical definition assigns a numerical value to the color emitted by a light source, measured in degrees of Kelvin. The Kelvin Color Temperature scale imagines a black body object— (such as a lamp filament) being heated. At some point the object will get hot enough to begin to glow. As it gets hotter its glowing color will shift, moving from deep reds, such as a low burning fire would give, to oranges & yellows, all the way up to white hot. Light sources that glow this way are called “incandescent radiators”, and the advantage to them is that they have a continuous spectrum. This means that they radiate light energy at all wavelengths of their spectrum, therefore rendering all the colors of a scene being lit by them, equally. Only light from sources functioning this way can meet the truest definition of color temperature .
This spectrum of color can have an autonomic response to the human body. “Energizing”. Light projections with enhanced Energizing and stimulating effects (potentially linked to the sympathetic ANS) considered to be obtained by using various combinations of colors in the warm-color range (Red, Orange, Yellow) with brainwaves modulations in the Beta range (13-20Hz), and rightward or outward light movements (Martel, 2001) 
Light projections with enhanced relaxing and pacifying effects (potentially linked to the parasympathetic ANS) considered to be obtained by using various combinations of colors in the cool-color range (Green, Blue, Indigo) with brainwaves modulations in the Theta/Alpha range (7-8Hz), and left-ward or inward light movements (Martel, 2001) 
The science supports that your autonomic nervous system can be influenced by light, so the next time you are walking late at night and feel a little anxious, look at the color spectrum the light is producing and see if it is warranted or if it is your ANS getting the best of you.
The color of light can also influence a term known as “Color Rendering Index” or CRI.
CRI is important when dealing with security. Another term is CPTED or Crime Prevention Through Environmental Design. CPTED brings lighting into the security realm when looking for forensic detail whether being remembered from a visual or from a technical (surveillance camera) perspective.
A simple definition of Color Rendering Index (CRI) would measure the ability of a light source to accurately render all frequencies of its color spectrum when compared to a perfect reference light of a similar type (color temperature). It is rated on a scale from 1-100. The lower the CRI rating, the less accurately colors will be reproduced .
Security assessments should provide empirical data in evaluating lighting. Empirical data coupled with CRI information provide a translational science to see what the impact might be on both visual and technical surveillance.
Lighting has many influences and the more knowledgeable you are the more empowered you can be to make decisions regarding your situation and your situational awareness.
When selecting lighting outside of your residence, consider the cool white light spectrum to provide good CRI in the event you have to describe something to law enforcement.
This information is being shared by a Board Certified Physical Security Professional for your “enlightenment”.
 Compiled from Physical Security Professional literature in support of assessments.