The rhythm of life is driven by the cycles of day and night, and most organisms carry in their cells a common, (roughly) 24-hour beat. In animals, this rhythm emerges from a tiny brain structure called the suprachiasmatic nucleus (SCN) in the hypothalamus. Take it out of the brain and keep it alive in a lab dish and this “brain clock” will keep on ticking, ramping up or gearing down production of certain proteins at specific times of the day, day after day.
