Why do i feel like i haven't slept even though i slept 8 hrs?

Could be: Overall sleep deprived or did not get a restful night sleep( did not cycle through the stages of sleep.Give it a few nights of getting 8 hours of sleep and see if it resolves, if not helping or gets worse see your your doctor.

Do you snore?: Consider sleep apnea. Sleep apnea is a common disorder in which you have one or more pauses in breathing or shallow breaths while you sleep. Breathing pauses can last from a few seconds to minutes multiple times per hour. As a result, the quality of your sleep is poor, which makes you tired during the day. Talk to your doctor to see if this or other issues may be having an effect in your sleep.