How did the American TV series make the bed so soft?

One kind of bed is filled with duck down instead of spring, which is very soft. I slept in the W Hotel, which was very comfortable. W Hotel, ICC Top Floor, West Kowloon, Hong Kong is about to open. Let's try it sometime.

The other is a waterbed, which is very comfortable to lie on just now, but uncomfortable to sleep for a long time.

Buying a pillowcase depends on its linear density. If it is above 400, it will be as smooth as silk.