Crying at Night...Potty or for Attention?

Hi, my 9.5 month old Australian Cattle Dog/Border Collie mix has been consistently waking us up in the middle of the night for the past few weeks now. He'll start whining and then pacing around the room to wake us up, usually around 4-5 hours after we all go to sleep. Tonight he woke us up after an hour (and here I am on posting this message).

When he wakes us up, we take him outside and he goes potty, then we bring him right back inside. He's never had a problem sleeping through the night before, so this behavior is really confusing to us. He should be able to hold it through the night, at least 7-8 hours.

Does he really need to go potty? Or is he manipulating us just to go outside? We exercise him everyday for an hour at the dog park, so he should be getting enough exercise. We haven't changed anything about his routine, so we don't really understand why this is happening.

Sounds silly, but could it be doggy adolescence? Any thoughts would be great.

It absolutely could be doggy adolenscence. They go through a period where they try to find out what they can get away with. 9.5 months sounds like just about the right time for it too!
Have you tried ignoring him through all the pacing and crying to see what he will do? That woud be my first try. You don't want to get into the habit of him getting up, and doing what he wants, when he wants. He needs to know that nightime is for sleep.
At that age he truely can hold it through the night so I wouldn't worry too much, as long as you take him out right before bed.
He probably goes when he gets outside because that's his habit, often walking into the cold triggers them to go, he probably doesn't truly have too.
Is he going more often during the day? If so I'd get him checked for a UTI just to be safe.
But if that isn't the case and it's not a physical thing, just ignore him for a night or two...act as tho you are in a deep sleep and just aren't waking up (even tho you will) I bet he just settles down and goes back to sleep. It may take a few nights tho, since he seems to be in the habit already of getting you up when he feels like it.

You have a mix of two very active dogs there. I don't think an hour a day at the dog park is enough excersise for him. You should take him on an additional brisk 45 min or more walk in the evening, or a game of ball in the yard if you have one to tire him out more. This incorporated with what Tinaweena said should improve things. Good luck!