The scientific reason why procrastination causes stress
Zeigarnik is not well known. Yet her research in 1920's Viennese coffee bars is the answer to why procrastination causes stress. She noticed a curious phenomenon. When a customer asked for the bill the waiters could easily recall the food that had been ordered. However, if the customer paid the bill, but then queried it a few moments later, the waiters struggled to remember anything about the order. It seemed that the act of paying brought a sense of closure in the waiter's mind and erased the order from their memories.
The Tests
Zeigarnik then tested this hypothesis in her laboratory, where she asked people to carry out a number of simple tasks (such as taking up counters or placing toys in the box), but some tasks she stopped the participants before they had finished. At the end of the experiment at the participants were told to describe all the tasks. As with her observations of waiters, unfinished tasks stuck in people's minds and so were far easier to remember. According to Zeigarnik, starting any activity causes your mind to express a kind of psychic anxiety. Once the activity is done and dusted your mind breathes an unconscious sigh of relief and all is forgotten. However, if you are somehow prevented from completing an activity you anxious mind quietly nags away until you're finished what you started.
So What?
So what? Well, as soon as you know there's a task to be done - or a task yet undone - your unconscious mind nags your conscious mind not to forget. And your unconscious mind isn't situation-aware, you can be nagged at times even when you can do nothing about the situation, yet be completely unaware when you do have the chance to do something - the time to remember you've run out of loo paper is when you're in the supermarket, not when you're delivering a sales presentation - or worse, sitting on the loo.
Taking Action
To pacify your unconscious mind, you need to have a system so that you know what you have to do, you know the next step in each matter, and you knew that the system works. And it's no good trying to cheat your unconscious mind. It knows whether you really have a working system!
If you're current system is suspect, I recommend Getting things Done by David Allen. I have been teaching time management for over 10 years, and this is by far the most practical book on getting a system that works. It doesn't solve procrastination, but it does give you piece of mind. Do it now, or there's one more thing to try to remember!