...sleep on your side.
Seems like common sense, right? People who sleep on their back and snore or have apneic episodes will quiet down immediately when they turn to their sides.
In fact, people with the most severe sleep apnea rarely, if ever, sleep on their back (unless side sleeping gives them pain) because it's nearly impossible for them to get adequate oxygen while they sleep supine. Even when they aren't consciously thinking of it, their brains are taking over during bedtime, signaling the body to sleep laterally (right or left side) in order to open that airway just a wee bit more so the flow of oxygen in and CO2 out can continue unobstructed.
Unfortunately, those with severe sleep apnea cannot get away with simply sleeping on their side; they will generally require a therapeutic device like a PAP machine to help them keep the upper airway open enough to allow for quality airflow.
But for those who solely snore or who have mild sleep apnea (as determined by an overnight polysomnogram--mild, moderate and severe are terms that are assigned based on specific objective measurement protocols, not educated guesses), a simple, effective solution may, in fact, be to sleep on the side.
According to the American Sleep Apnea Association, "Such people can eliminate or reduce airway blockage simply by learning to sleep on their side."
How can one achieve this when they are sleeping? After all, they aren't making conscious choices or decisions at this time.
The simplest way to achieve this is to place a tennis ball in a sock, then pin the sock to the back of your sleep shirt. Who could sleep on their back with this annoyance in place? It works!
If you want to get fancy, you can also buy a pajama top that is custom-built to "discourage supine sleeping," which is generally a sleep shirt with a tennis ball sewn into the back or tucked into a special pocket in the back.