It’s when the first metric increases or decreases in sync with the second, but with a lag between the first and second metric. The lag time can amount to one day, one week, or one month, depending on which chart view you’re using.

Here’s what it looks like:

This chart means that if you’re more productive this week, you will wake up later next week in 80% of cases.

And if you’re less productive this week, you’ll wake up earlier next week in 80% of cases.

If you see a correlation like this, you might conclude that you’ve been taking time to recuperate in the week following a major deadline. Good for you!