I have a 5 month old tibetan terrier who has just started to wake us up at night.  From day one she was fantastic at night never crying or making a fuss.  The last few nights she has started barking/whining from 4am in the morning until we get up at 6am to let her out. I don't think she is desperate to go out otherwise we would have accidents on the floor when we come down.  We can't work out why she has started to do this and would be grateful for any answers/advice.
Thanks.

Must be that time of year!  My pup doing axactly the same.  Theres been another post similar to yours on here in the last couple of days.  I reckon our little babies just want a sneaky bit of company.  Im sure it'll be something they outgrow

I hope so!

When you take her out, does she toilet?

If so, you should take her out because she should be able to relieve herself when she wants.  You might not have accidents on the floor because she is really trying to hold it in for you.  5 months is still a young pup...... 

Personally I would set my alarm for 15 mins before she usually gets you up, and take her out then.  That way she is toileting but she is not learning to "call" you to let her out.  When you have done that for several days, make it 15-30 mins later each night until you're going all the way through with no toilet - hey presto.

Our pup did this a few times and we finally worked out that it was when the central heating boiler started up - he heard it and thought someone was up and about and therefore he should be as well! I just took him outside for a wee, and apart from praising him for doing one, I ignored him and put him straight back in his cage. He doesnt seem bothered by it at all now and just ignores it.
Hope this might be of some help
Lizziel

At the moment when we get up with her in the morning we let her out and then she is so excited to see us she just wants to play.  I am concerned that if we get up and let her out in the night then she will not then settle and she will bark the house down if we put her back in the kitchen and go back to bed.

My dog does this every now and again and it's usually when he has a bad tummy. I just let him out as normal and don't make a fuss of him, then when he is done i put him back to bed as normal and say see you in the morning as i would have done when he first went to bed. That way he doesn't get any reward for waking us in the night, and luckily he only wakes us now if he has the runs. Which hasn't happened for a while now.

Personally, I think you should give it a go for a few nights.

Set your alarm for just before she usually wakes you up, then take her out.

Do not play with her.  Just be very calm and slow and quiet.

Take her outside, stand there and be very boring. 

Once she has toileted you can give a treat in slow, calm way.  Then take her back and put her back in the crate, with another treat.  (Treat for going in crate.)

Then leave her.  And don't return if she makes any noise.

The thing is - at the moment you said she is already barking the house down from 4-6am, so I don't understand what you've got to lose by taking her out at 4 - so what if she barks - she would be anyway??