Tiredness, Dizziness , Shaky Hands, Low Blood Sugar?

I am 5 11 and 150 lbs and 32 years old. I often feel tired or dizzy almost like my blood sugar is low. I sleep for 6 hrs a night and wake feeling great, but then 2-3 hrs later I feel like I haven t slept in a day. I used to have a great almost perfect memory but now often remember things incorrectly or don t remember at all. I don t know if it s related, but I ve noticed that my hands are a little shaky. I thought that was related to lot blood sugar, but it s pretty sparatic when I m shaky. I eat a fairly balanced deit, drink plenty of water, and exercise simi-regularly most of the year and snowboard heavily all winter. Why do I feel so out of it all the time?