What do you consider a lot? How is his appetite? What are your 4 temps and your humidity? Also please send a pic of your enclosure so that we can spot issues you may have which would cause excessive sleepiness.
Babies do sleep a lot, but lets check for some common problems.
What is your overnight low temp and what are you using to maintain that temp?
Any UV bulbs? Coil types?
Are you soaking daily?
Is the appetite good?
Was the baby started well with the wet routine, or is this a dry started baby?