Mattress flipping.

If you’re lucky enough to own a no-turn mattress, stop reading. If, like me, you buy your mattresses at the local Swedish superstore or at an unmarked storefront with broken windows, you’ll need to turn them once in a while. Ikea recommends that you turn your mattress every two to three months (after an every-two-week break-in period).

I use the side-to-side and end-over-end flip method, meaning I literally turn my mattress over every three months. Some people rotate and flip. Whatever works for you. But how do you remember which way you flipped it? The answer requires a little astronomy.

First, commit to turning your mattress every three months — specifically, when the season changes in March, June, September, and December. Next, think about the Earth’s position at each seasonal change.

In June and December (summer and winter), one end of the Earth is leaning toward the sun. Flip your mattress end over end.

In March and September (spring and fall), the Earth is more or less “standing straight up.” Flip your mattress long side over long side (or rotate if that’s your game).

Simple, and you don’t have to put it in your calendar or pin something to your mattress or roll dice or despair.