A basic functional unit of life on earth is time. All living things have biological clocks. They time what we do, synchronizing our internal functions with the world outside.
There are many clocks inside us. Some time out fractions of seconds, others months (menstruation) and years. Yet, perhaps the most important are circadian cycles - those of twenty four hours. They evolved so your inner functions fit night and day outside. Almost everything you do, think, and feel is affected by internal twenty-four hour clocks. Body Clocks literally time your life. Think of a car engine. If the timer is off, everything else goes off. Circadian medicine is about using our internal clocks wisely so that we keep healthy, and get what we want out of life.
