Your bird should be active during the day, although the occasional nap is fine. If this is a baby, it might sleep more. But it should still be exploring its cage and playing with toys. And this depends on how long you have had it. If you just got it, then the behavior is probably normal because he is settling in. If you have had him for a few weeks or longer, then he should probably be more active. If you are concerned about his health, you should take him to an Avian Vet.
Thank you for asking Lafeber,