Possible Reasons:
* Hunger/Thirst: While you mentioned she isn't going excessively during the day, she might be getting slightly hungry/thirsty in the middle of the night. Try offering a little extra water before bedtime and see if that helps.
* Bladder/Bowel Needs: Even though she's house trained, a slight change in diet or water intake could mean she needs to go out more often.
* Discomfort/Pain: Is there something uncomfortable in her crate? Could she be experiencing a minor ache or pain? Consider checking for any signs of discomfort in the crate.
* Separation Anxiety: Even though she has been crate trained, she might be experiencing anxiety when you're not with her. If this is the case, consider giving her a comforting blanket or toy from you, and gradually increase the time spent in the crate during the day.
* Environmental Changes: Has anything in her environment changed recently? New sounds, smells, or a change in routine could be affecting her sleep.
* Medical Issues: While less likely, a change in her sleep pattern could be a sign of a medical issue. If the problem persists, it's best to consult your vet.
What To Do:
1. Rule out medical issues: Schedule a vet visit to rule out any medical problems.
2. Observe and Record: Keep track of the times she barks/whines and any other related events (e.g., eating, drinking).
3. Consistency is Key: Stick to a regular bedtime routine and make sure the crate is comfortable and safe.
4. Eliminate Hunger/Thirst: Offer a little extra water before bedtime.
5. Nighttime Potty Breaks: Consider taking her out to potty around 3:30 am for a few nights to see if that solves the problem.
6. Desensitization: If separation anxiety is a concern, gradually increase the time she spends in the crate during the day. Start with short periods and reward her for calm behavior.
7. Comfort Objects: Provide a cozy blanket, stuffed animal, or her favorite toy to help her feel secure.
8. White Noise: A soft fan or white noise machine can help block out distracting sounds and create a calming environment.
9. Ignore the Whining/Barking: As tempting as it may be, try to ignore her initial whining/barking. If she continues after a few minutes, you can take her out to potty briefly, but go back to bed without any interaction.
Important Note:
It's vital to consult a veterinarian if your dog's sleep pattern changes significantly, especially if you notice other unusual symptoms like decreased appetite, lethargy, or vomiting. They can help rule out any underlying medical conditions.