Nice aircraft.
Flew on (two of) them, on a European trip, several years ago.
Their design is supposed to help with NOT having jet lag.
I believe the main difference is 25% higher cabin pressure allowed by the stronger carbon fiber fuselage. It’s comparable to being at 6000ft instead of the standard 8000ft. Or so I’ve read.
Other factors include higher humidity (or less dry air rather), LED mood lighting and larger windows than any other airplane. Also the cabin air comes from dedicated compressors and not bleed air from the engines.
,,, I did Auckland to Bangkok and back on Thai 787s in mid 2019. They’re a nice aircraft. I recall some years ago there was a problem that grounded them around the world for a short time - Yuasa new tech batteries. On one hand its good to know the problems are being picked up but on the other not so good to know they’re there to start with. Went on to Frankfurt and returned ex Milan in Thai A350-900s. I’d always found Boeings to be a bit more comfortable on long hauls but have to say the A350s have an edge in that regard now.