For the past few years, Eydís has been looking into it. She did a cross analysis on different measurements of cognitive workload with respect to the Icelandic flight industry. Cognitive workload, for the purposes of this article is synonymous with stress. The research indicates there are clear differences in measurements when an individual is rested or stressed. While the research focused on individuals in the aviation industry, the results can be applied to all people.
So, the answer to “Can stressed be measured?” is yes, most definitively. To get a more in-depth explanation of the indicators of stress, please read Eydís’ PhD thesis here
For more on the topic, read it here in Icelandic: https://www.ru.is/haskolinn/frettir/maeldi-alagseinkenni-i-tali
This research has been done in collaboration with ISAVIA and Icelandair.