Puppies are not stubborn, just confused. Here is a short bit I wrote for our training club:
Puppies need a simple, buckle collar and an appropriate weight, 6 foot leash. Heavy duty chokers and/or pinch collars are not appropriate and do not look macho-- they look moronic. You should not put a leash on the pup and then drag it around. Build a bond first; your puppy will happily follow you anywhere. You can allow the puppy to wear the collar and drag the leash around to get used to it, if supervised! If you choose to use an extenda-leash, please use it correctly. They can be good tools for going potty or getting a little more exercise when there are no other dogs or people around. Please do NOT use them to walk your dog around other dogs, at the vet clinic, etc. It is very poor doggy-etiquette to allow your sweet little Punkin to run out the 15 feet of an extenda-leash to every other person or dog in the vicinity. It can also be dangerous. Just because Punkin is friendly, does not mean the other dog (or person) is.
I doubt the 4AM time had anything to do with it. Put the leash on him at home, and stand in front, call him to you, praise and treat. You do not have to hold the leash, just let him drag it.