Do you know how some days you sleep for 5 hours and you feel like you had enough sleep and other days 10 hours are not even enough? Well, there is a science behind that.
What you do before you sleep, the amount of light that is in the room and the position you are sleeping in all play a role in how well you sleep at night. Some of these reasons are more obvious than others. Stress, for example, will raise cortisol in your body making it uncomfortable and while you are sleeping your brain will keep on thinking about different problems.
This is one reason you are not getting enough sleep although you are sleeping too much. Other valuable tips are in the link below.