There are a lot of other factors that affect your restedness other than hours of sleep
- Consistency: as a student, it's often difficult to have a consistent bedtime routine, exams, jobs, friends all mess with this
- I've done some reading on sleep in the past and some suggest that the hours of sleep you get before midnight, the earlier part of the evening is more condusive to non-REM sleep (that's the dream part). From my understanding, your body gets more rested during this phase, and could affect your quality of sleep. In contrast, if you sleep in later in the morning, you may notice that you remember your dreams more clearly
- Another point to add on consistency, if you are getting 5-6 hours of sleep on some days and 8-10 on other days throughout the week, the hours don't really offset each other. You will still feel drained from the days where you aren't getting enough sleep
- Quality of sleep: Is your room dark and quiet? Do you have your cell phone on? Distractions in your room often effect how deep you sleep. If you have a blue light (from an ipod player or whatever) glowing, that is said to be very intrusive to sleep quality. If you are listening to music or TV, those sounds can also affect sleep patterns.
- What do you do before bed: Are you active throughout the day rather than working out right before bed -which will leave your body wound up rather than relaxed? Are you watching intense tv dramas or studying for your hardest class? It's best to start slowing things down 1/2 hour - 1 hour before you want to go to bed. Lower lighting, softer sounds -kind of like if you were putting a baby to bed
- Medication: If you are on any medications, they can affect your sleep. Mine does make me drowsey throughout the day as soon as I stop moving. If it is impacting your life too much, talk to your doctor about switching
I'm not saying you don't have a sleeping condition and I'd definitely suggest still talking to your doctor about what's going on. These are just some things to consider. Our society tends to put sleep low on the priority list of all the things we need to get done throughout the day. As a student, I know getting good sleep on a regular basis is near impossible at times.
Hope you get some rest soon