5yr old behavior/tempertantrums

My son is 5 and in kindergarden. He has tempertantrums and is quite loud, I thought the problem was worked through while in pre school, but I don't think it was ever really resolved.  He is disrupting the entire class and getting upset about small things like if he miss placed something. Is it possible this behavior is due to a sleeping disorder? I haven't noticed any snoring or unusual sleeping, but he is exhausted(I thought it was due to his nap being abolished) at the dinner table his eyes tend to be very heavy and many times he askes to go to sleep around 7:30pm. If this is potentiallly a sleep problem where do I begin? Or any suggestions please. Thank You