Well…. I know that after a couple weeks the insomnia caused by stimulants is pretty much non-existent. I take 60mg (70mg being max daily dose) of Vyvanse daily and could sleep 24/7 if I wanted. Is he worried that if you may want the stimulant medication to help you stay awake thus making you dangerous on the road? I could see that being a factor. Shift work is never good for you. I work days, evenings and nights too and it really is hard on you. I take sleep meds to help me transition at times. Mostly from nights back into days or if my head is going one million miles an hour but when isnt it right? hahahahahaha
Have you told your Dr. the whole situation? Have him explain to you why he thinks its dangerous. Maybe theres something your missing… maybe theres something im missing.. if you still dont see eye to eye why not get a second opinion? It may take a bit longer but worth it in the end 
Love your avatar by the way! South Park ROCKS! Your little guys kinda reminds me of Maynard from Tool when he had his hair like that
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