Saturday, February 3, 2018

Ok, so I should blog more.

Here’s some interesting articles that I’ve recently read.

We know for sure that melatonin is a significant hormone for the human body and that not only do humans use melatonin but all living things also use melatonin.  Melatonin acts as an antioxidant, this mean melatonin is used by the body to repair damaged cells.  This occurs through the interaction of melatonin with mitochondria in individual cells.  The article recommends the following:

Turning off lights and especially screens about an hour before bedtime.
Going to bed and waking at the same time every day, even on weekends.

Avoiding light pollution from street lamps and other external sources of light, using light blocking curtains if needed.

Street Lighting Studies

One of the arguments thats regularly surfaces in dark sky advocates vs the lighting industry when concerning street lighting is how street lighting relates to safety and crime.  This issue comes about for several reasons, one is that the advocates for higher levels of illumination, along with greater uniformity, better colour rendering will claim reduced levels of crime.  It is expected that crime is reduced because better visibility will deter would be criminals will be deterred from crime because there will be a witness to their crime.  The corollary of course is that criminals will go to areas of poor illumination to commit their crime.  The dark sky advocates will claim that there is no proven relationship between levels of crime and levels of illuminance and to a high degree it is a correct claim.

There have been plenty of studies to ascertain the relationship between crime and illumination, most destined to be inconclusive because the reality is that crime is primarily driven by reasons other than the level of illumination.  The Rice Kinder Institute for Urban Research has recently released two reports around the influence of street lighting on safety and crime.  These two studies are a direct result of a program to convert street lighting in Houston to LED technology.  The two reports are:

The conversion to LED technology in street lighting is inevitable, the cost saving is far too favourable to ignore.  In every aspect of a street lighting inventory costs are found to be saved in electricity consumption and maintenance.  The studies address the above aspects that have come to the fore as communities have started to question the outcomes of the LED street light programs.  

An aspect of the study that is crucial to how the data is interpreted is how they assessed the level and nature of light, in fact in some instances this would be a critical factor when engaging the lighting industry, as the level and nature of light is completely reliant on human perception, and that makes the final assessment difficult as human perception is just that - perception,  Trying to quantify perception in terms of a proxy parameter is a fraught difficulty as it ignores confounding factors that have an affect on other aspects of behaviour, however the results will indicate trends that can later be analysed within the other factors.

This study used the density of street lighting as determined by linear extent of streets within an areal polygon defining a particular residential/business district.


The conclusion of the study looking a crime split the aspects of crime into crime against the person and crime against property.  When considering property crime it was found that where higher levels of street lighting density occurred there was in fact a higher level of crime and that “well lit places are also places of high activity that may attract some crime.”


The first study assessed the nature of the distribution of street lighting in Houston.  The most significant findings were the highest level of street light concentration was within the commercial/business district as well as an industrial/port area.  The lowest density of street lighting was to be found on the edges of town.

Other factors that came into play were based on the socio/economic mix of Houston where it was found that street lights were most prevalent in neighbourhoods of mixed socio/economic background and that neighbourhoods of higher median income have a higher density of street lighting.

Overall the papers are worth a read as not many researchers have taken this approach to analyse this type of crime data.