The following reasons may be responsible for dogs being restless and running around at night:

Hearing unfamiliar sounds Fear. Dogs' hearing is relatively sensitive. If they hear strange noises around them in the middle of the night, they will sound the alarm and start barking.

Feeling unwell. Dogs may grunt because of pain. Common causes include gastrointestinal discomfort, joint pain, fever, etc.

Lack of security. Puppies that have just arrived in a strange environment or suddenly lost the companionship of their mother dog will cry in the middle of the night because they lack a sense of security.

In addition, it may be because the dog slept too much during the day, wanted to go to the toilet, or was hungry, etc. Please consult a professional dog trainer for details.