Baz Luhrmann, in a pop song, remarked that worrying about a problem was like trying to solve an algebra equation by chewing gum. In short, anxiety and stress about work do not have any positive impact on your project. But, writing to deadlines is stressful, and it is likely to induce anxiety and worry. However, with a few simple techniques, this anxiety can be avoided, or at least minimised.
The surest way to avoid anxiety is to ensure that you know where you are going, and what you need to do to get there: imagine thinking that you have to get to somewhere, but have no idea where that place is, and cannot know how to get there! Anxiety! Sit down, and write a working schedule, that will keep your study time structured. Have time for reading, time for writing, and time for thinking. If you have a week to write, then schedule time for that week.
Set goals for every day. That might mean reading a certain number of pages in a given number of books. It might mean writing a certain number of pages every day. But whatever your schedule told you that you needed to do, set goals around that.
Make sure you hit your targets. If you plan to read 20 pages of Kant, then read, really read those pages and take those notes. If you set a goal of writing 600 words on Durkheim, then ensure that you hit that goal. Every small goal that you hit will increase your confidence in your ability to hit that major target, the end essay.
If you are doing all of the above, then give yourself credit by acknowledging that you are doing all that you can, that you are on schedule, and that you are able to meet targets. All you need is to take a few correct steps towards your final destination, to be positive about your ability, and you are on the way.
Sometimes, you simply need to leave the library, move away from the laptop, put the book down, so make sure to schedule in some fun too.