Best Memory Foam Pillow for Side Sleepers

What memory foam does under your head

Memory foam is viscoelastic. In plain terms, it behaves partly like a very thick liquid and partly like a spring. Press into it and it slowly flows around whatever is pressing on it. Lift away and it recovers. NASA's record describes an "open-cell, polymeric 'memory' foam material with unusual viscoelastic properties" that "returned to its original shape once the pressure was removed."

For side sleeping, that slow give is useful in two ways. First, the foam fills the space between your head and shoulder instead of bouncing back like a spring. That matters because, as a randomized trial of side sleepers put it, the main role of a pillow during sleep is to support the cervical spine in a neutral position. Second, a solid block can't shift around the way loose fill can, so its shape under your neck stays put.

The catch is that 'memory foam' covers a huge range of products. Shape, thickness and whether the foam is one block or shredded pieces all change how it feels. The label tells you the material, not the firmness or the height. Two pillows both sold as memory foam can feel nothing alike, which is why the rest of this page focuses on format and fit.

Origin story: airplane seats, not astronauts

You will often read that memory foam was invented for astronauts. NASA's own account is more specific. It describes "temper foam," with origins dating back to 1966, developed to absorb shock and offer improved protection and comfort in NASA's airplane seats. It came from NASA-funded aviation research, not from anything built for sleeping in space.

The same record notes, about a later medical seating product, that "the open-celled structure of the foam allows it to breathe, preventing heat buildup." Keep that in mind for the heat section below. Open cells help, but a dense block still surrounds your head with foam.

Solid vs shredded memory foam

This is the biggest decision within memory foam, and for a side sleeper it matters more than the brand.

Solid (one-piece) foam is a single block, either a plain rectangle or a contour with a raised edge for the neck. The WEEKENDER is a 5-inch rectangle. The Royal Therapy and UTTU are contour pillows with removable middle layers, so you get a choice of heights: the UTTU covers 3.2 to 5.2 inches across its settings, and the Royal Therapy comes in a 5-inch Queen and a 6.5-inch Extra.

Shredded foam is cross-cut pieces of memory foam in a zippered cover, often blended with microfiber. The Coop Original and DreamyBlue are both 8 inches listed and come with extra fill. You open the zipper and take foam out until the height fits your shoulder.

How the two compare for side sleepers:

• Height control: shredded wins. Solid foam gives you one height, or a few with removable layers.
• Consistency through the night: solid wins. Shredded pieces can shift as you move.
• Feel: solid foam has the slow sink memory foam is known for. Shredded fill feels more like a dense, moldable cushion you can punch into shape.
• Washing: Sleep Foundation's care guide says solid memory foam pillows should not be machine washed, because the foam can crack or degrade. Shredded pillows vary, so read the care label.

The research doesn't crown a shape. In a randomized trial, contour and regular-shaped foam pillows produced similar cervico-thoracic spinal slopes in side lying, and a study of 106 side sleepers found no evidence that a foam contour pillow had advantages over regular shapes. Cleveland Clinic chiropractor Andrew Bang, on the other hand, says cervical contour pillows work best for most people. With the evidence that mixed, let your shoulder width and how much you move decide.

If you aren't sure which height you need, Sleep Foundation suggests an adjustable pillow, and shredded foam is the most common way to get one. Our adjustable pillow guide goes deeper on setting the fill.

Does CertiPUR-US mean the pillow is non-toxic?

Not quite, and the certifier is careful to say so. CertiPUR-US certifies foams made without formaldehyde, ozone depleters, the phthalates regulated by the US Consumer Product Safety Commission, and mercury, lead and other heavy metals, with low VOC emissions for indoor air quality (less than 0.5 parts per million).

Three limits are worth knowing:

• It covers the foam, not the whole pillow. The cover fabric and any fiber blend are outside it.
• 'Low' is not 'none.' In its FAQ, CertiPUR-US answers a question about low emissions by noting there are few things on this planet that do not off-gas to some extent.
• It only covers flexible polyurethane foam. Latex foam is outside its scope, so a 'CertiPUR-US latex pillow' doesn't exist.

The label still means something. The foam is tested by an independent, accredited laboratory, and foam producers must recertify every six months for the first year and annually after that. Among the picks, the Coop Original, DreamyBlue and Royal Therapy list CertiPUR-US foam. The Coop Original also lists UL GREENGUARD Gold, a separate emissions certification with lower VOC limits. OEKO-TEX, which the Royal Therapy and UTTU covers list (the UTTU listing names STANDARD 100), is a third label again: OEKO-TEX describes it as a label for textiles tested for harmful substances, so it speaks to the cover, not the foam.

Heat is the main trade-off

Sleeping warm is the most common knock against memory foam. Cleveland Clinic's Andrew Bang says natural latex "offers support without heating you up like memory foam," which is one clinician's view rather than a measured comparison. No source in our register measures the temperature of a memory foam pillow.

What makes structural sense is this: a solid block surrounds your head with more foam and fewer air gaps than loose shredded pieces. Manufacturers try to offset it with ventilation holes (the WEEKENDER), gel infusion (the WEEKENDER again, and Coop's Eden) and cooling covers. Buyers are split on whether these work; Amazon's summary lists cooling as mixed for the WEEKENDER.

If you already know you sleep hot, shredded foam with some fill removed is worth considering, though no source here measures the difference. Our cooling pillow guide covers what helps and what is marketing, and the memory foam vs latex guide compares the two materials directly.

5 questions to ask before you buy

1. How wide are your shoulders? Sleep Foundation's side-sleeper guide says side sleepers usually need at least 4 inches of loft and broad shoulders may need more than 6. Its neck-pain page suggests 3 to 5 inches for side and back sleepers. No study has set an optimal height, so treat both as starting points. Wide frames lean toward the DreamyBlue or Royal Therapy Extra; small frames toward the UTTU. See our broad-shoulder picks if you are at the wide end.
2. How soft is your mattress? Cleveland Clinic's Andrew Bang says a firmer mattress needs a thicker pillow and a topper or pillow-top needs a thinner one.
3. Do you change position a lot? In a study of 664 working adults, people shifted position about 1.6 times per hour on average. If you roll onto your back often, an adjustable or contour pillow that also works for back sleeping helps; see our side and back sleeper picks.
4. Do you want to tune it, or set and forget? Tuners should buy shredded foam. Set-and-forget sleepers should buy solid foam at the right height.
5. Is neck pain the reason you are shopping? The evidence on pillow type is mixed, so prioritize height and shape. Our neck pain guide covers contour designs, and if pain persists, see a clinician.