Because headaches aren't the only reason for people wanting to sleep on their back. A couple of reasons I've heard: * Some feel sleeping on the back is the hea

Because headaches aren't the only reason for people wanting to sleep on their back. A couple of reasons I've heard: * Some feel sleeping on the back is the healthiest, most balanced position (I have gotten this advice from my doctor before, for example). Just because you don't get headaches on your side doesn't mean it's the most ideal sleeping position. * Some feel that their body specifically is in better balance on the back. For example, I noticed sometimes when I sleep on my side I get shoulder stiffness in the morning. It's not a big deal, but sleeping on the back prevents this. * Sleeping on your side can also contribute to facial wrinkle formation caused by squishing one side of your face (and normally we favor a side) for ~8 hours every night. There are pillows to let you sleep on your side and try to alleviate this, too, but at this point personal preference combined with other points like the ones above might just encourage one to try to sleep on their back. In the end I'm not very interested in why OP or anyone else wants to sleep on their back, nor am I interested in convincing them into or out of a certain sleeping position - that's not what this post seemed to be about. It specifically asked "How?" in the topic, not "Let's debate why or why not."