When looked at from a core biological perspective, I would say the answer has to be yes, but I might suggest a change to the language from the emphatic which feels emotionalized - "can and does absolutely" is not needed to convey the point. You might say something like: "our physiological window of tolerance changes throughout the day, influenced by numerous variables, conditions, and factors..." The physiology of arousal is complex... and is subject to innumerable body-mind-environment interactions. Circadian factors, interoceptive and exteroceptive (environmental, including neuroception, physical, and social conditions) factors, fluctuating psychophysiological factors (some of which are conditioning/memory states), nutrition/dietary status, sensory integration, patterns, etc. are all going to impact arousal levels. In my teaching I use multiple constructs to convey this - not just window of tolerance but "zone of arousal" and the resilience constructs noted above. The concept of the Yerkes-Dodson stress/performance curve is also useful since arousal and activation is healthy up to a point (eustress, and the point of decline is individual based on the topics in this discussion). In integrative medicine, some people like to look at it from the "energy management of the organism" perspective - it become an art form to learn appraise (recognize) and reappraise (evaluate) one's arousal level and interact with that in both an empowered and nurturing way. Finally, if you haven't read the paper on the neuroscience of the theoretical construct of window of tolerance, the PDF is available at Research Gate courtesy of the authors, here: https://www.researchgate.net/p...lex_emotional_trauma