If you sleep on your side, you'll need a firmer pillow with lots of filling to support your head and keep your spine aligned

Slumberdown Super Support Pillows 2-Pack - Firm Bed Pillow Neck Back Shoulder Pain Relief Side Sleeper - Hypoallergenic, Comfortable UK Standard Size (48cm x...
4.0
Amazon.co.uk

Silentnight Firm Support Pillow Pack of 2 - Side Sleeper Pillows for Sleeping Neck Back Orthopaedic Pain - Machine Washable Pillow Pair for Side Sleepers, White
4.0
Amazon.co.uk

TheComfortZone Perfect Orthopedic Pillow, Memory Foam Pillow, Cervical Contoured Neck Pillow, Side Sleeper Pillow, Pillows for Neck Pain, Anti Snore Pillow,...
4.0
Amazon.co.uk