In short: When you sleep on your side, the pillow has to fill the whole space between mattress and head – and that space is different for every person. It comes down to your shoulder width and how deep your shoulder sinks into the mattress. So above all, a pillow for side sleepers has to do one thing: have the right height and hold it through the night. Material, shape and size come second. Most standard pillows are too flat for side sleeping; most “side sleeper pillows” are one height for everyone.
Why is side sleeping the most demanding position for a pillow?
On average, adults spend 54% of their sleep time on their side, 37% on their back and 7% on their stomach – measured with motion sensors in 664 adults. So side sleeping is the norm, and its share increases with age. For the pillow, it’s also the hardest case.
On your back, your shoulder lies flat; the pillow only bridges the curve of your neck. On your side, your shoulder stands on the mattress, and without a pillow your head hangs down sideways. The distance between mattress and ear is 8 to 14 cm, depending on build. The pillow has to fill that distance – not roughly, but so that your cervical spine lies horizontal.
Too flat, and your head tilts toward the mattress: the muscles on the upper side of your neck, above all the sternocleidomastoid, push back all night. Too high, and your head tilts away: now it’s the trapezius between neck and shoulder that works. Both are documented in EMG measurements. Muscle activity is lowest at the height derived from your individual geometry.
What height does a side sleeper need?
The honest answer: the one that fits your body and your mattress. If you need a number: under load – meaning with your head on it, after a while – the right height for most side sleepers is between 5 and 12 cm. That’s a range of seven centimeters, and within it, a single centimeter is already the difference between straight and bent.
Two factors decide where you fall in that range:
- Shoulder width. Measured from the base of your neck to the tip of your shoulder. On your side, this distance lies between the mattress and your neck – the broader, the more height.
- Sink depth. A soft mattress or a shoulder zone takes away part of that distance, and so does a heavier upper body. That’s why changing your mattress often means changing your pillow too.
Why height charts still only get it roughly right is explained in our guide to pillow height.
What about your shoulder – does it belong on the pillow?
No. The pillow supports your head and neck; your shoulder rests on the mattress. If your shoulder is on the pillow too, it gets pushed up, your neck loses its support, and the pillow is suddenly too high for your head. This is the most common reason wide 80 cm pillows work poorly for side sleeping: they invite you to pull your shoulder onto the pillow.
A well-shaped pillow ends at the shoulder or has a cutout there. At hana, this part of the shape is called the edge angle: the slope at which the pillow tapers off at the shoulder, so the shoulder rests freely while the neck is still filled.
Which material works for side sleepers?
Material is secondary, but it’s not irrelevant. It decides whether the height that’s right when you lie down is still right at two in the morning.
A 2021 meta-analysis of nine high-quality studies with 555 participants found a small but significant advantage of rubber or latex pillows over other materials with regard to neck pain – mainly because they keep their shape. For more on materials and their physical properties, see our comparison of pillow materials.
How can you check whether your pillow fits side sleeping?
Most reliably with a photo taken from behind while you lie down. The step-by-step check is in our guide to pillow height.
Two everyday clues that your pillow is too flat: you put your hand under the pillow at night, or you fold the pillow in half. Both are attempts to add height.
Do you switch between side and back?
Then your pillow has to fit in both positions. On your back, different factors count than on your side – above all the shape of your upper back. How far apart the two heights are differs from person to person.
How do you get the right height for side sleeping?
Answer a few questions about how you sleep and how you are built – with a side photo if you like. From them we calculate your pillow core with its neck-roll height, head cradle and edge angle. Made in Switzerland, with you in about 1 week. 100-night trial.
Frequently asked questions
Which pillow is best for side sleepers?
One whose loaded height exactly fills the distance between mattress and head, and that holds this height through the night. That’s a question of fit, not brand. Shape-stable materials such as latex or cold-cure foam hold their height more reliably than down.
How high does a side sleeper pillow need to be?
Usually between 5 and 12 cm under load, depending on shoulder width, mattress and body weight. A chart based on shoulder width only gets the right height roughly.
Why do I wake up with a stiff neck as a side sleeper?
The most common mechanical cause is a pillow that is too flat or becomes too flat overnight: your head tilts toward the mattress, and your neck muscles push back. A side photo taken while lying down shows whether that’s the cause for you – and if the discomfort persists, see a doctor to have it checked.
Do side sleepers need a special side sleeper pillow?
Not the long body-pillow kind. A regular pillow with the right height and a shoulder cutout is enough. A knee pillow between your legs can also help keep your pelvis straight.
What pillow size is right for side sleepers?
50 × 70 cm or 40 × 60 cm. At 80 cm wide, your shoulder slides onto the pillow and your neck loses its support.
Sources
- Skarpsno E.S. et al. Sleep positions and nocturnal body movements based on free-living accelerometer recordings. Nature and Science of Sleep 9:267–275 (2017). doi:10.2147/NSS.S145777
- Pang J.C.Y. et al. The effects of pillow designs on neck pain, waking symptoms, neck disability, sleep quality and spinal alignment in adults: a systematic review and meta-analysis. Clinical Biomechanics 85:105353 (2021).
- The impact of pillow height on neck muscle activity: a pilot study. Sleep and Breathing (2024). doi:10.1007/s11325-024-03219-6
- Gordon S.J., Grimmer-Somers K.A., Trott P.H. A randomized, comparative trial: does pillow type alter cervico-thoracic spinal posture when side lying? Journal of Multidisciplinary Healthcare 4:321–327 (2011).
