The genetic network of the circadian clock coordinates the communication between the organism and its environment

Circadian clocks regulate a plethora of physiological processes including the sleep/wake cycle, blood pressure and body temperature. Such clocks enable organisms to adjust to the 24-hour day/night cycle resulting from the rotation of the earth. Virtually all living beings have a circadian clock and in the case of multicellular organisms, most cell types house such a clock. The clock mechanism consists of a stable network of genes and proteins that mutually regulate each other, thereby not only establishing a self-sustaining clockwork but enabling this clock to adjust to periodic environmental changes such as availability of light and access to food.