Sometimes all I want to do is sleep for days... what is wrong?

I get tired very very easily.. i veen get sleepy when my friends come over and i have to talk with them. Sometimes when im at work I count the hours until i get home to sleep. I get sleepy during odd hours like 12pm ... yesterday I was so sleepy after work! i slept for 3hrs then i went to a family reuinion and by... show more I get tired very very easily.. i veen get sleepy when my friends come over and i have to talk with them. Sometimes when im at work I count the hours until i get home to sleep. I get sleepy during odd hours like 12pm ... yesterday I was so sleepy after work! i slept for 3hrs then i went to a family reuinion and by 8pm I was falling asleep on the couch! Its like a constat heaviness on my eyes, tiredness, lack of concentration, stress I dont know! Im only 20yrs old/active/eat healthy/student! what can be wrong? sometimes i even hibernate! i sleep for a whole day including nights... but there are some days when i feel good and i do lot so things. I am not depressed or anything..but this sleepiness and tiredness is killing me!!!! I JUST WANT TO G T SLEEP!
***this has been happening for abt 1-2yrs.***
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