Daylight and Earth’s 24-hour clock are at the very heart of evolution. “The Inner Clock” offers a rich history of what makes us tick, so to speak, paired with fascinating modern discoveries ...

The brain has a master clock that is set by exposure to sunlight and darkness. This circadian rhythm is a roughly 24-hour cycle that determines when we become sleepy and when we’re more alert.

Here’s what to know about the twice yearly ritual. The brain has a master clock that is set by exposure to sunlight and darkness. This circadian rhythm is a roughly 24-hour cycle that determines when ...