It’s generally thought that it’s best to sleep on your back, as this keeps your spine in a neutral position, reduces heartburn and leads to fewer wrinkles (as your face isn’t squashed into the pillow), but this does mean you’re more likely to snore.
However, some people are advised to sleep on their sides, such as pregnant women, for whom there may be blood circulation benefits, and those with breathing conditions, who may find their airways clearer.