Hi there,
From what I can understand this can be for a number of reasons:
1. that at night your dragon is seeking security and snuggness. do you have a hide for him? if not it sounds like he might appriciate one. if you cant buy him one right away a shoebox with a door cut out with a section of towel/blanket insid can suffice until you buy a proper one.
2. some dragons enjoy a good dig every now and then. but as yours is just at night id imagine this isnt it.
3. uh-oh. you've got a girl dragon who wants to lay. dragons can lay infertile eggs. are you sure your little one is a boy?