It seems like such a simple little thing, but it can really throw off your day. The most productive employees in the world find themselves under deadline and falter. The pressure of just knowing it's out there takes over from the part that would normally just relax and calmly accomplish the task. Maybe it's the name - deadline. It certainly doesn't sound very friendly.
Deadlines are different though.
Deadlines bring order to the job. They allow you to plan ahead, and judge how much time you should spend on each task. What's more, in the work world there's no way to avoid them, so for your own happiness and piece of mind, it's best to make friends with the deadline. After all, although it is sometimes hard to recognize it, the deadline is a valuable tool that can make your job a lot easier. To begin with, accept that every task has a deadline.