Both animals and plants have internal timekeeping mechanisms with which they are able to measure time. These "clocks" control the timing of such diverse processes as seasonal breeding cycles and the sleep‑wake cycle in humans. Knowing how such "clocks" work helps us to comprehend the temporal order of the living world and also tells us how to avoid the practical problems resulting from jet‑lag and shift work. Disturbance to these clocks can lead to major illnesses such as depression and cancer and can be treated by the new techniques of “chronotherapy”.

RETIRED: Removed Status Nov 21, 2016 (M.Golding)