Lurcher started whining in the night

[chickensaresafehere]

We got a rescue lurcher over a year ago now,she settled in quite well,gets on with our JRT & seems very happy.
But over the past few months she has started to either wake us at 4/5am whining at the bedroom door or sometimes earlier.Me or dh take her downstairs & let her out,sometimes she will do something,sometimes not,most of the time when we take her downstairs she jumps back on the sofa & settles down again?!
We have tried lots of different things - walking her last thing,putting aher coat on(in case shes cold),feeding her later/earlier.
Even if we have a late night & she goes out before we go to bed ,she still does the whining thing!!
If it's about 5ish,dh will just open our bedroom door & she will jump in our bed & go back to sleep until we get up.
Do you think she is feeling insecure on her own at night? House is open plan,JRT is crated (she is crate trained & gets anxious if she is given the run of the house),she happily sleeps all night with no disruption.
Should we try bringing her bed up to our bedroom (I know she will try & get on our bed though).
I've run out of ideas!!