I pulled my pillow out of the pillowcase one morning and almost recoiled. It was yellow. Not slightly off-white — yellow yellow. Like old newspaper yellow. The kind of yellow that makes you question every night of sleep you have ever had on that thing.

I washed it that day. Halfway through the dryer cycle I checked on it and it was a wet, lumpy, sad brick. I thought I had ruined it. I had not. I just did not know the two tricks.

Trick One: Two Pillows at a Time

Washing machines need balance. One pillow throws the spin cycle off and the pillow ends up waterlogged because the machine cannot spin it out properly. Two pillows balance each other. If you only need to wash one, throw in a couple of clean towels for counterweight.

Use warm water, not hot. Hot water can melt synthetic filling. A small amount of liquid detergent — half what you would use for clothes. Too much soap and your pillow never fully rinses, which leaves a residue that attracts dirt faster.

Trick Two: Tennis Balls in the Dryer

This sounds fake. It is not. Put two clean tennis balls in the dryer with your pillows. As they tumble, the tennis balls bounce around and beat the pillow filling apart. This breaks up clumps, prevents lumping, and restores fluff. Dry on low heat. It takes longer — about an hour — but high heat can melt synthetic fibers.

Check every twenty minutes. Fluff the pillows by hand if you see any stubborn clumps. The tennis balls do most of the work but the occasional manual fluff helps.

How Often?

Every three to six months. Your pillow collects dead skin cells, sweat, drool, and dust mites. The yellowing is mostly sweat and body oils oxidizing. A pillow protector under your pillowcase stretches the time between washes significantly, and a protector costs about five dollars.

The morning after I washed mine — actual white again, actually fluffy — I woke up without the neck crick I had been blaming on stress. It was just a dirty, lumpy pillow.