I spent two years waking up with a stiff neck. Some mornings I could not turn my head to check my blind spot while driving. I blamed my mattress, my desk setup, my phone usage. It did not occur to me that the problem was the pillow until I stayed at a hotel and woke up completely pain-free for the first time in months.

I came home, looked at my pillow — a $12 polyester-filled lump I had owned since college — and realized I had been sleeping on garbage. What followed was a six-pillow testing saga that cost me more than I want to admit.

Why the Wrong Pillow Hurts Your Neck

Your spine should be straight when you lie on your side — a continuous line from your tailbone to the top of your head. If your pillow is too high, your neck bends upward. Too low, and it sags downward. Either way, you spend eight hours with your neck muscles straining to hold an unnatural position. They do not get to rest. You wake up sore.

The right pillow height depends on your sleeping position and shoulder width. Side sleepers need a thicker pillow to fill the gap between the shoulder and the head. Back sleepers need a thinner pillow that supports the natural curve of the neck without tilting the head forward. Stomach sleepers need the thinnest pillow — or sometimes none at all.

What Actually Helps

• Adjustable fill. Shredded memory foam or buckwheat pillows let you add or remove filling to dial in the exact height. This is better than a fixed loft because your perfect height is probably not what the manufacturer decided.
• A contour shape. Pillows with a raised edge under the neck and a depression for the head keep your cervical spine aligned. They look weird. They work.
• Cooling cover. Memory foam traps heat. If you sleep hot — and neck pain already makes it hard enough to sleep — get a pillow with a cooling gel layer or a breathable bamboo cover.

After the hotel pillow revelation, the one that finally worked for me was an adjustable shredded memory foam pillow. I removed about a third of the filling, tested it for one night, removed a little more, and by night three I had it dialed in. The neck pain was gone within a week. I have not woken up unable to turn my head in over a year.