Why is my dog restless at night?

[releasethehounds]

Looking for a bit of advice. My border collie is 3 years old and is generally a very healthy, lovely natured dog. She sleeps on her own bed which is located in our bedroom and upto now we've never had a problem with her at night - in fact, she's so quiet you forget she's there.

However, this has all changed over the last week or so - she will start to pace around at night and make snuffling noises which gradually progress onto small barks and then really loud barking until one of us lets her out! I don't think she needs the loo as she's only a young dog and normally has a concrete bladder which she holds for hours! When we do let her out at night she just walks around the garden sniffing the air for a couple of minutes (she may do a little wee but I think it's just marking rather than a necessity) then waits at the door to be let in again.

It's getting like having a newborn again with all the night disturbances, but I can't just let her stay in the house and bark continuously as she will wake the DDs (she has a very loud bark). I did originally think that she was too warm in the bedroom so I leave a window open and the door is always ajar so she can get to the (much cooler) kitchen downstairs.

I think that now she's getting into a bad habit and getting spoilt by this night time attention and I want to break it before we go mad from sleep deprivation!

Any ideas would be appreciated.

TIA.

[releasethehounds]

bumping for any ideas!

[DrHolmes]

How much exercise does it get per day, how much food etc