Why do some people become more aggressive when tired?

Question

Why do some people become more aggressive when they are tired? I've been thinking about this question for a few days and my 'hypothesis' is that the neural activity in the prefrontal cortex lessens as the brain prioritises the other more primitive parts of the brain. Is it also so that the amygdala becomes more active when tired for some reason?

I've tried to search for answers on Google but can't find any satisfying ones. Optimally, I'd like to see brain scans and have them explained, but maybe that's asking for too much.

Answer 1

From Poor sleep as a potential causal factor in aggression and violence

• In most people poor sleep will not evoke actual physical aggression, but certain individuals, such as forensic psychiatric patients, may be particularly vulnerable to the emotional dysregulating effects of sleep disturbances

• The relation between sleep problems and aggression may be mediated by the negative effect of sleep loss on prefrontal cortical functioning. This most likely contributes to loss of control over emotions, including loss of the regulation of aggressive impulses to context-appropriate behavior.

• Other potential contributing mechanisms connecting sleep problems to aggression and violence are most likely found within the central serotonergic and the hypothalamic-pituitary-adrenal-axis. Individual variation within these neurobiological systems may be responsible for amplified aggressive responses induced by sleep loss in certain individuals.

Answer 2

being tired affects the brain in some ways similar to being drunk, it is not so much making you aggressive as impairing your ability to suppress aggression. The amygdala routinely produces aggressive impulses which the prefrontal overrides/suppresses. lack of sleep impairs its ability to override. https://walkerlab.berkeley.edu/reprints/Yoo-Walker_CurrBiol_2007.pdf