Challenging behaviours or behavioural crisis in relation to autism is a topic that has graced this blog before (see here). Covering a whole spectrum of issues ranging from aggression (self and/or directed against others) to various other quite undesirable presentations (such as smearing) quite a lot of behaviour can potentially fall into this description.
Without heading too far into the possible [often very individual] reasons as to why challenging behaviours occur and their meaning (see here for more information), I think most people would be satisfied by the idea that such behaviours are not normally random or without purpose. Whether communicative or as a response to external stimuli, behaviour - even challenging behaviour - normally serves some kind of function. The trick is finding out what function.
So it was that the paper from Christopher Smith and colleagues  explored this issue and concluded that: "problem behavior was most likely to occur when both task demands (discriminative stimuli) were presented and when the setting event (fatigue) was operative." Smith et al report results for 3 individuals, all males, all diagnosed with autism and accompanying learning disability and all with "a history of behavior problems that became more frequent when they were fatigued and when task demands were given." Various steps of investigation were included covering a functional assessment of each participant, a functional analysis of behaviour based on times of fatigue or not and using demands or not and also: "a multicomponent intervention package developed for each individual based on the assessment information derived from Steps 1 and 2." As previously indicated, in times of fatigue + demands, problem behaviour predominated more than on other occasions.
I don't want to get to heavily into any psycho-babble explanations when it comes to the Smith findings based on the results of just 3 participants and other methodological factors. The main point that: fatigue + setting event, specifically the requirement to complete a task = an important combination when it comes to the presentation of challenging behaviours in the context of autism is however potentially important. More so when one considers that issues pertinent to the presentation of fatigue such as sleep quantity and quality have already found a place in autism research history (see here). Indeed, the recent results from Andréane Lambert and colleagues  are testament to that.
Although the concept of fatigue is quite a nebulous term, I'd like to think that there is more research to do in this area specifically with autism in mind. Take for example the results reported by Claro and colleagues  who "examined whether the fatigue level of children diagnosed with cri du chat syndrome was associated with the expression of autistic symptoms." They concluded that yes, "children who exhibited high levels of fatigue were more likely to express high levels of autistic symptoms." Whether those 'autistic symptoms' translate into severe behavioural problems is still to be determined with the wider autism spectrum in mind.
Without also wishing to make connections where none might exist, I'd put forward the idea that beyond just instances of fatigue, the concept of chronic fatigue might also be something to investigate, at least with some autism in mind. I've previously introduced the idea that a diagnosis of autism is seemingly protective of nothing when it comes to comorbidity (see here) and allied to some very preliminary reports of chronic fatigue syndrome(s) (probably plural) appearing alongside autism (see here) I'd be interested to see if this was generalisable to many more cases or not and what this might say for challenging behaviours in specific individuals.
Music: Blondie - The Tide Is High.
 Smith CE. et al. Fatigue as a biological setting event for severe problem behavior in autism spectrum disorder. Research in Autism Spectrum Disorders. 2016; 23: 131-144.
 Lambert A. et al. Poor sleep affects daytime functioning in typically developing and autistic children not complaining of sleep problems: A questionnaire-based and polysomnographic study. Research in Autism Spectrum Disorders. 2016; 23: 94-106.
 Claro A. et al. Association between fatigue and autistic symptoms in children with cri du chat syndrome. Am J Intellect Dev Disabil. 2011 Jul;116(4):278-89.
Smith, C., Carr, E., & Moskowitz, L. (2016). Fatigue as a biological setting event for severe problem behavior in autism spectrum disorder Research in Autism Spectrum Disorders, 23, 131-144 DOI: 10.1016/j.rasd.2015.12.003