I Wake Up Too Early (3:30 Am) And Cannot Get

I wake up too early (3:30 am) and cannot get back to sleep. I go to bed at 10:00 pm. During the day and evening, if I am sitting or reclining in a darkened room I will fall asleep. I want to sleep longer at night so this does not happen. My thyroid and iron levels in my blood have been tested. I am on hormone replacement therapy (for 3 months) and it seemed to help earlier, but not anymore. I am age 56.