Educational resource
You know how you fall asleep. Not how the night goes.
Most people change position many times a night. The last posture you remember — the one you settled into — is a bad sample of the hours that follow.
Read the overview ↓This page is educational. It is not medical advice.
Back
Supine sleeping is the posture researchers most often study for snoring and airway.
Side
Side is the most common adult posture, and left versus right appears in reflux studies.
Stomach
Stomach sleeping is less common and is usually discussed for comfort and neck strain.
The perception gap
What you remember is not the night.
People overestimate time in their preferred position. You fall asleep on your left and assume that is the night. It often is not.
You can settle on your left side and spend hours on your back. The last posture you notice is a single sample. The night is a sequence.
That gap matters when a clinician talks about left versus right for reflux. The geometry has been measured; whether you stayed there has not. Read the left-versus-right reflux measurements — educational background, not a product claim.
The literature
What researchers actually look at
Snoring and airway
Supine sleeping is widely studied in snoring and airway research. Gravity and tongue position are part of that work. A position pattern is not a diagnosis. If you gasp, stop breathing, or wake unrefreshed, see a clinician.
Reflux
The geometry of left versus right has been measured in published GI research. A paper in the American Journal of Gastroenterology, discussed on our reflux page, reported roughly 76% less acid exposure on the left side than the right in that study. That is AJG literature — not Komori data. For GERD, see a clinician.
Comfort and pain
Findings on overnight comfort and pain are mixed and individual. A position that eases one person's shoulder can bother another's neck. Komori does not treat pain. Persistent pain belongs with a clinician.
Pregnancy
Clinicians often discuss left-side sleeping in late pregnancy. This page does not advise a position. Talk with an obstetric clinician about what is right for you.
When to see a clinician
See a clinician for pain that does not settle, gasping or pauses in breathing, sleep that never feels refreshing, or reflux that does not ease. A webpage cannot replace that visit.
Wearables
What a watch cannot see
Wrist position is not torso position. You can sleep on your back with a hand on your chest, or on your side with an arm under the pillow. A watch on the wrist does not know which.
More on that gap: Apple Watch vs. a sleep monitor and contactless sleep monitors compared.
Keep reading
Related reading from the Komori Care blog.
If you want the night written down
A two-piece system is being built — a sensor above your headboard and a base on the nightstand — to record back, side, and stomach through blankets. No camera.
Komori is a general wellness device in development. It is not a medical device.
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