Causes may be excess intake of caffeine,alcohol intake,obstructive
sleep apnea,shift duties,
disorders of the hypothalamus,nervous system
disorders like brain tumors, Circadian rhythm sleep disorders and some medications.
I feel that you should consult a sleep specialist and get polysomnograms(sleep study) done to find a confirmatory diagnosis.
Hope it helps.Take care and pls do keep us posted on how you are doing.