India, Nov. 14 -- Most people choose a pillow the way they choose a bar of soap: by how it feels in the first ten seconds. Soft or firm, cool or cosy, done. Height barely comes up, even though it's the measurement that decides whether your neck spends the night in a neutral position or in a quiet struggle.

That's why two people can buy the same well-reviewed pillow and have opposite experiences. One wakes up fine. The other wakes up with a stiff neck and a tingling arm. The pillow didn't change. The sleepers did. Here's what the research says about pillow height, why your sleep position changes the answer, and how to find a pillow that fits you.

Why height matters more than softness

A pillow has one basic job: keep your head and neck i...