I recently went on a trip to California.
Coming from the East Coast, this was a three-hour shift west. To adjust to California time, I needed to delay my circadian clock. One catch, though: my flight out was extremely early in the morning. That meant, like it or not, I was going to advance myself as I set out on the journey.
Let’s back up a little. We talk about directions your internal clock can shift as advances or delays. Think of advancing as hustling your clock along, making your circadian rhythms more like those of people in time zones east of you. Delaying, on the other hand, is like a temporary slowdown for your clock, making your rhythms more like people living to your west. Light at different times of the day advances or delays you, depending on your clock’s state when you’re exposed to it.