The Master Clock of Clocks

A tiny timekeeper in the brain

There are two clocks in the body. One resets every morning with the rising sun. The other does not reset at all. It accumulates, recording the passage of years. 

For the past 20 years, these two systems have been studied separately. Increasingly, however, scientists are finding that they are connected: as we age, the daily clock is disrupted, making it harder to sleep well. Evidence now suggests that the converse is true: if you slow the daily clock, the aging clock may slow too. 

Deep within the brain sits a structure no larger than…