Ask if you can shift to day shift...I don't know where your from but in the UK your employer has to accommodate any changes relating to work while your pregnant without dismissing you or changing their attitude towards you. If this is not an option like alaysha says you are going to need to find things to help you wind down, maybe try getting some black-out blinds/curtain as I know the light mornings/days will not help you get the rest you need speak to your DR and see if they can suggest anything suitable for you to take while your pregnant and above all try not to stress...this will not help you wind down nor get a complete rest. Hope that helps :)
Maybe think of a different job or ask your doctor for something to help you sleep. I worked nights during my last pregnancy and when I would get off (at about 10-11 at night) I would go home and relax for an hour of two before I went to bed. Eat something filling, take a long bath, read until your eyes get tired, etc. If you still can't sleep then maybe take some benedryl or tylenol pm.