This is Dr. David
you could have something called chronic fatigue syndrome.
you might be having poor sleep and not getting into REM sleep when you do sleep.
you could have bad sleep apnea which can affect your sleep.
you might need a sleep study to see if you are getting into deep REM sleep properly when you do sleep.
there are treatments for sleep apnea and chronic fatigue syndrome
a panel now wants to call chronic fatigue syndrome a new name: systemic exertion intolerance disease
you can read more there
let me know if you have questions.