Yes! I think you might need to see you MD, ask yourself a few important questions.... Do you snore? Do you dream? Do you wake up alot during the night? Have you been told that you wake up gasping for air? If you have yes to any of these questions, then it is possible you could have sleep apnea. It is very common. This occures due to a few things, a person that is somewhat over weight, short neck or just snore have issues wiht falling asleep during the day. MD can order you to have a sleep study done, this is were they test you while you are sleeping and see if you ever fall asleep deep enough to rest. This is something millions of people suffer from adn can be dangerous over time. If you do infact have sleep apnea, this could also be making you Oxygen level dip down durning the night, which is hard on your heart, lungs and other body organs. I hope this was a help, GO SEE YOUR DOCTOR! You will be amazed at how much better you can feel!
my suggestion is that you talk to your doctor about this problem. you may have an underlying problem that needs to be addressed. He/she may need to order a sleep study. Although you say you get 8 hours of sleep a night, it may not be a fitfull sleep. Your doctor is the best judge of that.