The Best Sleep Position Is the One That Keeps Your Airway Open
Search for the best sleeping position and you will get a lot of advice about spines. Side sleeping for your back, a pillow between the knees, do not sleep on your stomach.
All of that is reasonable as far as it goes. But for a large number of people the more important question is not what position is kindest to the lower back. It is what position keeps the airway open, because that is the one that decides whether the eight hours you spend there are actually worth anything.
Why your back is the problem position
When you lie on your back, gravity works against you. The tongue and the soft palate fall backward toward the throat, the space behind them narrows, and the tissue that has to stay open all night has less room to do it.
This is not a small effect. Snoring is consistently worse on the back. In obstructive sleep apnea it is worse still, and in roughly half of the people who have it the breathing events are at least twice as frequent lying on the back as they are on the side. For some, the apnea is essentially a back sleeping problem and close to absent otherwise.
That pattern has a name, positional sleep apnea, and it has a treatment that does not involve a machine or an appliance: stay off your back.
Side sleeping, and which side
For most snorers, sleeping on the side is the single most effective free change available.
If you have reflux as well, the left side has the better case. The stomach sits to the left and the junction between it and the esophagus ends up above the level of the stomach contents in that position, which makes it harder for acid to travel the wrong way. Night time reflux fragments sleep, often without waking you fully, so this is worth more than it sounds.
Stomach sleeping keeps the airway reasonably open, which is why some snorers drift into it, but it costs you elsewhere. Your head is turned roughly ninety degrees for hours, which is hard on the neck, and the side of your face and jaw is pressed into the mattress all night.
The pillow does more than you think
The goal is simple to describe and easy to get wrong: your head should sit in line with your spine, neither propped up nor dropped down.
Side sleepers need a thicker pillow than they think, because the gap between the ear and the shoulder has to be filled. Too thin and the head drops toward the mattress all night.
Back sleepers need a thinner one. This is where airway and comfort collide. Stacking two or three pillows bends the neck forward and pushes the chin toward the chest, which narrows exactly the space you are trying to protect. If you sleep on your back and wake with a sore throat or a dry mouth, look at how many pillows are under your head.
Raising the whole upper body is different, and better. Propping the head with pillows bends the neck. Raising the head of the bed a few inches, so your whole torso is on a gentle incline, keeps you straight and helps both snoring and reflux. Blocks under the bed legs or a wedge do this properly.
How to actually stay off your back
Deciding to sleep on your side does not work, because you are not conscious for the part that matters.
The oldest trick still works: put something on your back that makes lying on it uncomfortable. A tennis ball in a sock pinned to the back of a sleep shirt, or a small backpack worn loosely. It feels ridiculous and it is effective, because you do not have to wake up for it to work. You just roll back over.
There are commercial versions, including devices that buzz when you turn onto your back. They work on the same principle and cost considerably more than a tennis ball.
Give any of these a couple of weeks. The first few nights are disturbed and then it stops registering.
What I see in the chair
Position leaves traces, and a dentist has a good view of them.
Morning jaw soreness, worn or flattened teeth, and clicking in the joint often come up in the same conversation as snoring, because people whose airway is compromised at night frequently clench and grind, and one explanation is the jaw being thrust forward to reopen the airway. The mouth records a lot about how somebody has been breathing and coping overnight, which I went through in how your mouth reflects stress, sleep and inner health.
A dry mouth most mornings tells me you spent the night breathing through it, which is its own problem and usually a sign the nose was not doing its job. The nasal breathing side of this, including who should not go near mouth tape, is in mouth taping and nasal breathing.
Where position is not the answer
Position is a lever, not a cure. If you snore loudly on your side as well as your back, if anyone has seen you stop breathing or gasp, or if you wake unrefreshed no matter how you slept, that is a different conversation and it needs a proper evaluation rather than a new pillow. The difference between snoring that is harmless and snoring that is not is in snoring, when it is harmless and when it is a red flag.
One important exception: none of this applies to babies. Infants should be placed on their backs to sleep, every time, and that guidance is not in tension with anything above. If it is your child who snores, the signs worth acting on are in when a child snores.
The short version
Sleep on your side, preferably the left if reflux is in the picture. Get the pillow height right for the position you actually sleep in rather than the one you intend to. Raise the head of the bed rather than stacking pillows. And if you are a confirmed back sleeper who snores, spend three dollars on a tennis ball before you spend anything else.
Position sits in the same category as bedroom temperature and light timing: free, unglamorous, and worth more than most of what gets sold. The order I would work through those in is in the sleep biohacking guide, and the temperature numbers are in the cold room rule.