I think it's safe if you are not stressed out by it and if you are able to sleep. If you're having a hard time sleeping then it might get a little difficult. Can you speak with your employer to get you on a set schedule? It would be better if your schedule was exactly the same each week then it would be easier to set a sleep routine.
you should have no issue unless it's causing you too much stress, or is too physically demanding. In early pregnancy you should be just fine doing what ever it is that you do for work by the second or third trimester if you have a physically demanding job you may need to slow it down a little or get some help.
Like cocacolapanda said there shouldn't be any issue to the baby at this stage in the pregnancy. However, you may want to get on a more regular schedule since in a couple of months you are going to feel like a walking zombie. Schedules are nice for that since you can plan accordingly.