Hypnos is a great brand we bought a Hypnos bed 24 years ago and it is great.
I replaced the mattress some time back with a John Lewis own brand one (Sinclair pocket springs)
A few hundred pounds but worth it.
Thi year I invested in a John Lewis feather and down mattress topper. Wow! Like sleaping on a cloud.
We also bought a cotton duvet cover, and WOW again! I still have the Argos polycotton one so every other week when we change it it is heavan to go to bed!