Lately I Have Felt Lethargic And Lacked The Energy That

Lately I have felt lethargic and lacked the energy that I normally have. I get sleepy whenever I sit down at a meeting. For the past few days, I have had a headache, and I rarely ever have had headaches in the past.
I go to sleep immediately at night but do not stay asleep long enough. Lately I have had about 4 to
4 1/2 hours of sleep each night. I do not think I have sleep apnea. I never snore or wake up during the night. I sleep soundly but not long enough. Once I am awake I cannot go back to sleep.
I am wondering if this lethargic feeling could be a low blood count or a vitamin deficiency. I don't have any stress or anything to be depressed about. My blood pressure is normal. Please give me some medical advice about these symptoms.