Any idea what could be wrong?

For some reason he's been sleeping way too much lately... Yesterday he slept 12 hours and today he slept 21. According to his mom he woke up around 7 today and made himself eggs for breakfast then went back to bed. He doesn't remember any of this. He's been forgetting the simplest things and also HUGE things that he shouldn't forget... He has never done drugs and he never will, just so you know. He wants to be in the DEA, so that's definitely not it. Does anyone know what could be wrong?