Left or Right Side Sleeping: Comfort and Pillow Fit

Should I sleep on my left side or my right side?

For most healthy adults, sleeping on the left or right side is a comfort choice, and neither side is a rule. Pick the one that feels better and let your body switch during the night.

A pillow does the same job on either side. So the fit steps below work whether you favor left, right or both.

Sleeping on the left side vs the right side

Left and right side sleeping feel different mostly because of habit, which shoulder is sorer, and which way your partner or the window faces. One small study of 71 people found that people with a side preference showed a slightly lower upper eyelid on the side they slept on. That’s a cosmetic finding, not a reason to change sides.

Example: if you always fall asleep on your right but wake up on your left, nothing is wrong. Switching sides is normal.

Who may have a reason to prefer one side

People who are pregnant, have heartburn or reflux, or have a sore shoulder may be told to favor one side. Left is often mentioned for pregnancy and heartburn, and right can feel worse for reflux. Those are questions for a midwife or doctor, not something a pillow page can settle.

If none of that applies to you, go with comfort.

What makes a pillow right for a left side sleeper?

A good side sleeper pillow fills the gap between your ear and the outer shoulder, so your head stays level. Lying on your side, your nose should point straight ahead, not up or down.

Loft: the gap between ear and shoulder

Loft is the pillow’s height once your head is on it. Wider shoulders need more of it. A small study of nine healthy people linked the best pillow height to shoulder width, and a study of 21 adults rated a middle height (10 cm) as the most comfortable. Both are small, so treat the numbers below as a rough start, then adjust.

Example: a side sleeper with wide shoulders who wakes with the head tilted down probably needs a taller pillow.

Firmness: firm enough not to sink

Medium-firm to firm usually holds the head level. Too soft and your head sinks. Too high and it tilts up.

Your mattress matters too. A softer mattress lets your shoulder sink, so you may need a lower pillow. A firm mattress may need a higher one.

Why left and right need no different pillow

A left side sleeper and a right side sleeper have the same gap to fill. Choose by shoulder width and mattress, not by side.

For more depth, see our guide to pillow height for side sleepers.

Which pillow shape and fill suit side sleeping?

Memory foam, latex, down and down alternative can all work for side sleepers; the right one depends on how firm and how warm you want it.

These are general traits, and they vary by brand.

Memory foam and contour pillows

Memory foam is a slow-recovering foam that molds to your head. A U-shape contour or L-shaped design adds wings or a raised edge for side support. Check that the edge sits comfortably against your shoulder.

One option is Derila Ergo, a contoured memory foam pillow with front support wings and a removable cooling cover, 54 x 36 x 12 cm. The maker says the wings support the neck for side, back and stomach sleepers. The maker hasn’t published a study of Derila Ergo itself.

Latex, down, down alternative and kapok

Latex is a springy rubber foam that tends to sleep cooler. Down is soft feathers from ducks or geese. Down alternative is a synthetic fill, and kapok is a plant fiber from a tree seed pod. Soft fills suit lighter frames; broad shoulders may need firmer ones.

Adjustable fill

Adjustable fill means shredded foam or fiber you can add or remove to match your loft. It suits anyone still finding their height. See adjustable loft pillows compared.

Cooling and breathability

Hot sleepers should look for cooling covers, open-cell foam or latex. The maker of Derila Ergo says its cover and breathable foam help keep it cool and dry. Look for CertiPUR-US or OEKO-TEX labels, which are material safety labels.

Queen size and king size pillows give combination sleepers more room to roll.

Does a pillow between my knees help side sleepers?

A pillow between your knees can keep your hips and legs stacked instead of twisting. It’s an easy add-on for most side sleepers.

In pregnancy, a pillow between the knees is a common home tip. It appeared in two case reports of pregnant women with pelvic pain, which is very early evidence. Ask your midwife or doctor first.

Knee pillow or body pillow

A thin, firm knee pillow stays put and suits most people. A long body pillow also lets you hug your chest, which helps if you tend to roll forward. It takes more bed space.

Pets and partners in the bed

Tuck the knee pillow between your legs before you settle, and keep your head pillow on your side of the bed. A partner or pet who steals space may do better with a pillow strap or a separate body pillow. Example: a dog that sleeps at your feet won’t bother a thin knee pillow.

How can I test a pillow at home before I commit?

You can test a pillow at home with a five-minute side-lying check and about a week of use.

A five-minute side-lying check

Lie on your side and have someone take a photo, or use a phone propped on a shelf. Look for:

• Head level, nose pointing straight ahead
• Lower shoulder not squashed under you
• Jaw relaxed, not pushed sideways

Then give it about a week and note how you feel each morning.

Trial periods, returns and warranties

Check the return window, who pays shipping, and whether it must be in original packaging. Derila Ergo advertises a 60-day trial with a full refund. The conditions: you ask within 60 days of receiving it, fill in a contact form, wait up to 3 business days for an RMA number, and ship it back with tracking in original, undamaged packaging. Shipping costs aren’t refundable. Refunds are issued within 14 days of the parcel being received and inspected.

It arrives vacuum-packed, and the maker says to leave it 6-8 hours to expand.

Check the current price and return terms on the official site if it fits your shape.

See Derila Ergo on the official site60-day money-back guarantee

When should a doctor’s advice come first?

See a doctor first if you’re pregnant, have heartburn or reflux, have shoulder pain, or have symptoms like loud snoring or numbness. A pillow is a comfort choice, not a treatment.

Pregnancy

Ask a midwife or doctor which sleep position and support pillows suit you. Advice changes through pregnancy.

Heartburn or reflux

Ask which side to favor and whether raising your head helps. Don’t assume left or right will fix it.

Shoulder pain

Lying on a painful shoulder may need professional advice. Example: if the shoulder you sleep on aches by morning, get it checked before buying anything.

Snoring, breathing pauses and lasting neck pain

Loud snoring, gasping or pauses in breathing, and daytime sleepiness are signs that need a doctor. See one too for numbness, tingling, weakness in an arm, pain after an injury, or neck pain that doesn’t improve within a week.

How do I care for a side sleeper pillow and when should I replace it?

Care depends on the fill, and most pillows last roughly 1 to 3 years.

Washing by fill type

• Memory foam and latex: don’t machine wash the core. Spot clean and air it out.
• Down and down alternative: many can be machine washed. Check the label, dry fully and fluff.
• Derila Ergo’s cover is removable and machine washable warm, per the maker.

Use a pillow protector and wash cases regularly. Our guide to cleaning pillows by fill type has more.

Signs it is time to replace

Replace it when it stays flat or lumpy, smells, or you wake sore again. See when to replace your pillow.

Where to go next

Left or right is mostly a comfort call, so the fit matters more. Our practical guide to pillows and neck comfort puts it all in one place. For a shortlist, see best pillows for side sleepers, or read about knee and body pillows for side sleepers.