Fetal Position Sleeping: What It Means for Your Neck and Pillow

The fetal position is side sleeping with your knees drawn toward your chest and your back curved forward. For pillow purposes it counts as side sleeping, so the pillow has to fill the gap between your shoulder and your head.

Key takeaways

• Fetal position is a form of side sleeping, so shoulder width and pillow height matter most.
• We know of no study that shows the fetal position by itself causes or prevents neck pain. Treat any claim that it is simply "good" or "bad" with caution.
• A Pillowise fitting uses three measurements plus your sleeping position and mattress firmness. A provider near you takes them for free.

Is the fetal position bad for your neck?

It depends on how you curl. Many people tuck the chin toward the chest, which bends the neck forward for hours. A pillow that is too low lets the head drop toward the mattress. One that is too high tilts it away. Both can leave you stiff in the morning.

Evidence on the fetal position itself is thin. Most pillow-height research looks at side sleeping in general, usually in small groups of healthy adults, so it shows association, not cause. See our post on side sleeping, shoulder width and pillow height.

How high should my pillow be if I sleep curled up?

High enough to keep your head level with your spine, not higher. That height depends on your shoulder width, neck circumference and neck height, and on your mattress. A soft mattress lets the shoulder sink and calls for a lower pillow. A firm one does not. Weight is not part of the Pillowise fitting, but a heavier person sinks deeper, so a provider may adjust.

Not sure your current pillow fits? Read how to tell if your pillow is the wrong height.

What can I try tonight?

1. Loosen the curl. Let your chin move away from your chest a little.
2. Check your neck line. Ask someone to look at you from behind. Your head should sit level, not bent toward the mattress or the ceiling.
3. Note how you fall asleep. That is the position used in a fitting. If you are unsure, choose side.

How does Pillowise approach it?

The Pillowise algorithm combines shoulder width, neck circumference and neck height with your sleeping position and mattress firmness, then picks one of 7 sizes. It indicates the right size for about 95% of people. Providers check your position on the pillow and adjust when needed, for example during pregnancy. You can try the manual measurement on our pillow height calculator. A fitted pillow is an adjunct to care, not a treatment.

After you give the pillow 7-10 days to adjust, you have a 30-day comfort guarantee from the purchase date. You can exchange the pillow for another size or return it for a refund. Return shipping is paid by the customer, and shipping charges are not refunded.

Find a provider near you

Pillowise is sold through chiropractors, physical therapists and licensed massage therapists. The measurement is free at every reseller. If you wake with pain, numbness or stiffness that does not go away, see your own provider first.

Find a Pillowise provider near you for a free measurement.

Providers: you can offer fittings in your practice. Learn how to become a reseller.

Thijs van der Hilst, physiotherapist
Co-founder of Pillowise