It is best to sleep on your side or on your back. Sleeping on the tummy is to be avoided as it can cause neck and back pain. If you like to sleep on your side, a deep pillow with good support is recommended. Or you can choose two slim pillows, the top one being feather if you not allergic to it.
If you are pulling your pillow into your neck or putting your hand underneath your pillow, you are looking for more support and maybe best to add another pillow if you are just using one.
If you sleep on your back, one pillow is preferable but many medical conditions demand that we use two if not three pillows. A good night’s sleep can easily be disrupted by a painful neck. The correct pillows can relieve this pain and it is always good to change your pillows regularly as the weight of our head flattens them, leaving you without that support you are needing. Treat yourself to new pillows, it will prevent that stiff and achy feeling the following morning.