The effect of light on our biological clock is important as it influences many aspects of our physical and emotional well-being. This biological clock is regulated by light and darkness, by the daily cycles of night and day and the time we spend asleep and awake.

In the morning, as the sun comes up, light levels increase, the colour of light shifts towards cooler colour temperatures, and we wake up and become active. On the other hand, in the evening, as the sun goes down and the colour of light shifts towards warmer colour temperatures, we unwind, relax and prepare for sleep.

Our body’s hormone levels rise and fall with these light cycles. Cortisol production increases with morning light and decreases throughout the course of the day. Melatonin levels increase as darkness sets in and decrease as morning approaches. In our modern society, we spend much of our time indoors – at home, in a school, office, shop or hospital. Those who have to stay indoors for significant parts of their time under static lighting conditions run the risk of disrupting their biological rhythms.