An important part of making a wearable computer un-obtrusive is the user interface and the way it interrupts the user. The amount of interruption that have to be made on the users primary task should be minimized. Usage without interruption is of course best for the performance of the primary task but is often not possible as many tasks that the wearable computer is involved in do need interaction with the user. It is therefore important to understand what type of interruption that will benefit the user most. The question about which interruption that causes the least amount of stress for the user is as important as which interruption that gives the best performance. This paper continues on previous work where performance of the users was measured for different types of interruption. In this paper subjective data is analyzed to understand how to build user interfaces for wearable computers and head mounted displays that considers stress and other subjective variables.