last month coming back from HKG in 53K unusually I was cold. I was sleeping without the duvet as normal, so when I looked for my duvet my seat mate had mine as well as his so it must have been cold. I never need a duvet no matter what airline I travel with, it was a pleasant change and I did go back to sleep without a duvet. No way was the cabin temp was 21/22c range.
John