I read you problem it is not difficult for me, I can solve your proble very easily.
I am also work daily 12 hours from 8:00am to 8:00pm and i wake up 7:00am and sleep 12:30pm without reast.
First of all you do some practice, when you will ready for sleep, you image you are free from life, you dont take any tention in your mined. (any type of tention like job, salary, people, lover, parent, or bosses) just you are ready for sleep.
And secondly you will take a table of vitamine it is also improve your tiredness.
I hope you well get better when you try this one.
And please reply me what is the result of my advice.
HI, I AM M. ALI, 30 YEARS OLD, HOLDING MASTER AND LLB DEGREE, WORKING AN INTERNATIONAL ORGANIZATION, VISITED AROUND 25 COUNTRIES. LOOKING GOOD FRIEND