Most people put more thought into choosing a mattress than a pillow, then wonder why they wake up with a stiff neck. A pillow has one job: to keep your head and neck roughly in line with the natural curve of your spine while you sleep. Get that right and the rest of the night tends to look after itself.

Which pillow does that depends almost entirely on how you sleep. Side, back and stomach sleepers need very different shapes and heights, and a pillow that feels lovely for two minutes in a shop can leave you sore by morning if it does not match your position.

Start with your position, not the pillow

A pillow that suits your neighbour's bad back may be completely wrong for you. The aim is simple: head, neck and upper spine should sit in a line that mirrors your back's natural curve. Prop your head too high and your chin drops towards your chest; too low and the neck bends backwards or sideways. Either way, the muscles at the back of the neck spend the night holding on, which is one reason mornings can feel worse than bedtime.

So before you shop, notice how you actually sleep. Most people have one main position with brief shifts during the night, and that main position is the one to plan around. If you genuinely move between your side and your back, an adjustable pillow lets you compromise rather than choosing one at the expense of the other.

Side sleeping: the most common position

Sleeping on your side is comfortable for many people and keeps pressure off the lower back, provided your pillow fills the gap between the side of your head and the mattress. That gap is roughly the width of your shoulder, which is why side sleepers usually need the thickest pillow in the house. Shoulder width varies enormously, so treat any recommended height as a starting point rather than a rule.

If the pillow is too flat, your head dips, your neck bends sideways and the top shoulder rolls forward. If it is too thick, the neck bends the other way and the upper spine curves. A pillow tucked between the knees is a small addition that keeps the pelvis level and often eases the lower back.

Getting the height right

Ask someone to check your alignment, or prop a phone on a shelf and take a photo. Your ear, shoulder and hip should fall roughly in one line, and the tip of your nose should point straight ahead rather than up or down. Adjustable pillows — shredded memory foam, or a layered design you can unzip and thin out — make this far easier to fine-tune than a solid block of foam.

Back sleeping: support the curve, not the crown

On your back, the spine sits at its most neutral and the pillow's job is smaller: support the inward curve of the neck and cradle the head without pushing the chin forward. Back sleepers usually do best with a medium to thin pillow, or a contoured one with a shallow neck roll and a dip for the head.

Too much loft is the common mistake here, especially for anyone who has borrowed a chunky pillow from a side-sleeping partner. A pillow under the knees takes some tension out of the lower back if you tend to arch. Softer fillings such as down or down alternative work well in this position because they compress under the weight of the head.

Stomach sleeping: the position that fights back

Sleeping on your front means your head is turned to one side for hours, often with the neck tilted back at the same time. The lower back tends to arch as well, because the abdomen sinks into the mattress. It is the hardest position to support properly, and if you can gradually train yourself onto your side or back, it is worth the effort.

If you are set on sleeping on your front, use the flattest pillow you can tolerate — or none under your head at all — and try a thin pillow under the pelvis to reduce the arch. To shift positions over time, start the night on your back with pillows wedged against each side, so rolling onto your front takes deliberate effort.

Pillow types and who they suit

  • Solid memory foam. Firm and consistent. Good for side sleepers who need steady height, though it warms up and softens with body heat, which some people dislike.
  • Shredded memory foam. You can add or remove filling to change the loft by a centimetre or two, which makes it the most forgiving choice if you are unsure.
  • Latex. Springy, holds its shape and breathes better than foam. Usually among the more expensive options.
  • Down and feather. Soft, low profile and easy to squash into shape. Suits back and stomach sleepers, but needs daily fluffing, flattens over time and can aggravate allergies.
  • Down alternative or hollowfibre. A similar soft feel without the feathers, and generally machine washable.
  • Contoured or cervical. A raised edge or neck roll with a hollow for the head. Popular with back sleepers; some side sleepers find them too shallow.
  • Buckwheat or millet. Mouldable and firm, holding whatever shape you push it into. Heavier and noisier than most fillings.

How to test a pillow before you commit

Lie down on a bed in the shop rather than pressing the pillow with your hand, and give it a full five to ten minutes on your usual side. Check the returns policy before you buy, keep the packaging, and allow a week of nights before deciding — a new pillow can feel strange at first. Small adjustments are worth trying too: a pillow protector adds height, while removing some filling lowers it.

Your mattress matters as much as your pillow. A soft mattress lets the hips sink, which changes how much support your neck needs; a firm one often calls for slightly more loft. And most pillows lose their spring long before they look worn. Fold one in half — if it stays folded, it is past its best.

When to seek advice

A well-chosen pillow can make nights more comfortable, but it will not resolve persistent pain, numbness or tingling in the arm or hand, or neck pain that followed an injury. If symptoms last more than a couple of weeks, or come with weakness or headaches, speak to your GP, a physiotherapist or another qualified clinician rather than experimenting with pillows. The guidance here is general and not a substitute for personalised medical advice.

Photo: Letícia Alvares / Pexels