3.5 out of 5 stars

The sun rises every single day and has done so for the past few billion years. This source of energy has played a pivotal part in the development of life on Earth and not unsurprising, it has been a focus of our collective attention for time immemorial. Many cultures have worshipped it or have tracked its regular path through the heavens and tried to elucidate meaning from it.

As the sun has been a central part of almost all the Earth’s inhabitants, lots of creatures have evolved in tandem with it, including us. Research has shown that the sun is key to our mental well being, sleep, immune systems and circadian rhythms. Too much sun is bad for us as it can cause skin cancers but then so is too little, those that rarely see the sun do not generate enough vitamin D that is essential for their health.

One of the biggest disrupters to our health in the modern day is artificial light. Ever since the light bulb was invented, cheap affordable light has been available to all so we have retreated indoors turning pallid in the glow of the modern screens. Office lighting is a good example. The output from the ceilings lights is fairly poor, you only get a fraction of light, around 200 to 300 lux, which is nothing when you compare it to the amount light on a bright day which can reach around 100,000 lux. All of these effects are cumulative, and if you live in northern Europe, then you are much worse off in winter because of the very short days.

I liked this book a lot, it does what a good popular science book should do, gives you a good overview of the subject and touches on lots of different subjects without becoming too academic. On certain elements, for example, on our body clocks and how to improve lighting for those on shift work, in particular, Geddes explores them in a little more depth. Worth reading

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