The mammal body clock: a layered system of multiple internal timers that create daily rhythms

The circadian clock operates with a periodicity of approximately 24 h.

• The mammalian circadian system consists of a hierarchical structure with a central clock in the suprachiasmatic nucleus (SCN) and peripheral clocks throughout the body.
• Key clock genes in mammals are involved in complex feedback loops that regulate the circadian rhythm.
• Each cell has its own independent clock, but cells in the SCN are coupled to form regional oscillators that synchronize to create a unified tissue rhythm.
• The coupling between regional oscillators is important for the stability and adaptability of the circadian clock.
• New molecular tools are aiding in the understanding of the mechanisms behind the circadian clock's function.

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