When the schnauzer is a puppy the puppy schnauzer sleeps around 15 to 20 hours per day which some of that or most of that time is at night.
When the schnauzer is a full grown adult schnauzer dog they usually sleep for around 12 to 16 hours per day with most of that also being at night.
Puppies tend to sleep more than adult dogs do which is true for any breed of dogs.
Just like human babies and kids sleep more hours than adults do.
Puppies need more sleep than adult dogs do just like humans need more sleep when they are babies and kids than adults do.