Severe drowsiness and aches?

For about 2 or 3 weeks my friend has been severely drowsie all the time. He will take naps for 3 to 4 hours and still be very tired. He says that the feeling you get when you first wake up stays for 20 minutes. He feels like hes always in a hot room, his eyes burn, and he is achey. what could this be? please give me some answeres I'm scared something could be seriously wrong.