Dendrobium dropping leaves - can you regulate it?

[Ffion]

Two of my dendrobiums, Oriental Smile Fantasy and Rainbow Dance are currently undergoing winter treatment with night temperatures going down to 45-50F. Both are shedding their leaves and soon I'll have leafless canes only. From what I've read it's quite normal but at the same time I've seen lots of photos of both flowering WITH nice green leaves- which would be my preferred option. Are they dropping the leaves because of the cold treatment? Is it true that higher temps (so cool not cold) also stimulate flowers but at the same time the leaves are retained?

---------- Post added at 11:08 AM ---------- Previous post was at 10:51 AM ----------

And also- do these (and D.nobile and nobile type hybrids) need a day/night temperature difference during winter rest or is constant low temp OK? Right now I'm constantly moving them out and in