Memory foam and related products have claims like
TEMPUR Mattresses create a custom fit for your body, virtually eliminating painful pressure points and reducing your body’s need to toss and turn in search of a comfortable, pain-free sleeping position.
Visco-Elastic memory foam mattresses are commended by medical professionals across Scandinavia and used in the health sector throughout mainland Europe due to their widely recognised therapeutic benefits.
Many of these mattresses are also sold as "orthopedic", implying some kind of beneficial effects. There are some notes about memory foam and pressure ulcers, but little about back pain.
I have only been able to find two very small, potentially relevant studies, and I can't even tell what the "selected bedding system" is in the second article without access.
So: Is there any evidence that memory foam mattresses help reduce back pain? Either during night-time or during the day after sleep.