Circadian Rhythm

The circadian rhythm is our bodies’ internal time-keeping clock. It controls our sleep and wakening, and is influenced by light. The circadian rhythm adjusts to our environment’s daily light–dark cycle and, therefore, changes throughout the year. A regular waking time in the morning strengthens the circadian rhythm and can help with sleep onset at night.

Light affects the production of melatonin so that as daylight ends and night-time begins the levels of melatonin rise telling our body that it is time to sleep. It is the level of melatonin which decreases as we get older, making us vulnerable to insomnia as we age.