Light is as essential to us as the air we breathe. We have known since time immemorial that light affects our well- being, but not the how or why. We are slowly starting to find out more and more about the underlying mechanisms.

Like many people, Gemma Venhuizen has noticed that light influences her mood. On dark days she feels down, and on sunny days she cheers up. She has researched the influence of light on our wellbeing, looking at exactly what it does to us, mentally and physically. For this book she spoke to psychologists, sleep researchers, dermatologists, biologists and engineers to find out more about the universal need for light (and darkness) and to take stock of the degree to which light is crucial to good health.

From sun worship to seasonal depression, Gemma Venhuizen has studied many facets of light. Her book was written out of a fascination for this everyday yet magical phenomenon. There are few authors who can make complex scientific material intelligible without simplifying it, and write beautifully and engagingly too. Science journalist Gemma Venhuizen is one of them.

She shows how bright light can lessen our appetite and increase our libido; explains why light therapy is just as effective as antidepressants and how old people with dementia can benefit from the right kind of lightning.