why do i feel tired even if i got 10 or 11 or 12 hours of sleep ?!

I had the same probolem. Its probably because your Iron level is low and this makes you feel really tired and out of energy. You should go to the docter and get an iron test but thats usually it and its really simple to solve. All you have to do is go to your local pharmacy and get Iron tablets and if you get the right kind they taste GREAT!!! :)

My own expirience

Oh the dreariness of getting old. Actually, plenty of people feel like this. If there is actually a problem, hypersomnia (excessive sleeping) can be a sign of depression or narcolepsy, but that's about it medically. If you think you could have depression which is incredibly common for teenagers, look it up. It probably isn't narcolepsy. Things that people do to try to avoid sleeping too much include avoiding sweets/caffeine in the few hours before bed time, getting a better mattress, and EXERCISE. Exercise is huge. It's unbelievable how much energy you can gain just by doing a decent jog every day or two. Also, I have found that I have to train myself to sleep less. It sucks for a week to only sleep 7-8 hours a night when you are used to 10+, but you get used to it and it gets easier.

You probably aren't sleeping WELL enough, try some sleep remedies or even medication to help.

Fatigue can be due to dehydration, under eating and even low iron.

1.over sleeping
2. your body isnt falling into deep enough sleep to recover
3. could be you have low blood sugar

11 or 12 hours of sleep is too much, after that many hours, you tend to stay groggy and slow for longer. Its probably because of your diet. You may be eating to many processed, bleached foods loaded with preservatives and artificial ingredients. This is not healthy food for the body, it slows you down, makes you feel ill and sometimes we get so used to eating that crap that feeling bad becomes the norm and we dont even know what it feels like to feel great and energized anymore. Cut bleached flours, pasta's and rices out of your diet. This are carbs and if you eat too many of them they will make you feel drowsy. Milk based products like soups or dairy can also slow you down as the body was not meant to process and digest cow's milk. Eat wheat and whole grains, bleach free foods, lots of fresh veggies and fruits. Foods like leafy greens (salads, spinach, herbs) and broccoli give you energy as well as fruits enriched with vitamin C and all vitamin B (potatoes are rich with numerous vitamins from a to z including all your B vitamins) B vitamins give you an energy boost. But yeah basically you need to change your diet and probably get a little exercise to wake your body up and get your blood pumping. A good brisk walk/jog for 30 min a day will suit you well.

trail mixes with nuts, raisins and cranberry's are great energy booster's too! Eating these foods will help you WAKE UP feeling great and ready to go, when you eat healthy, you dont tend to need an extra artificial boost to wake up. Diet and exercise are the life changing remedy for just about any illness or ailment out there, Scientific fact.