My 6 month old beagle/husky mix sleeps in a crate at night. For the past few weeks, he's been waking up between 3:30 - 4 am. We started ignoring this and he generally goes back to sleep after a few minutes. But then he will wake up an hour to an hour and a half later, and we usually get up to let him go out to the bathroom at that point. Any suggestions on how to get him to start waking up on our schedule so we don't have to get up so early? Is this just a puppy issue that he will outgrow? Besides giving him a lot of exercise in the evenings, which we do, are there any other suggestions to get him to sleep longer?