Table 1.

A summary of the literature exploring circadian factors in IBD-related models

Model	Reference	Circadian Factor	Summary of Findings
Tissue	Palmieri et al. 2015; [60] Weintraub et al., 2020; [61] Liu et al. 2017 [62]; Mosna et al. 2021[63]	Clock gene expression in colonic mucosa, leukocytes	Altered expression in IBD and in inflamed mucosa, associated with increased endoscopic disease activity, inflammation
Rodent	Eum et al. 2023; [64]	Circadian disruption (constant light exposure)	Increased intestinal epithelial permeability, altered expression of tight junction proteins
	Tran et al. 2021; [65] Voigt et al. 2014; [66] Liu et al. 2021; [67] Preuss et al. 2008 [68]	Circadian disruption (shifting light/dark cycles)	Increased intestinal epithelial permeability; altered gut microbiota; reduced resistance to colonic injury
	Kyoko et al. 2014; [69] Stokes et al. 2017; [70] Liu et al. 202167	Clock gene mutation	Altered expression of tight junction proteins, altered resistance to colonic injury; altered intestinal regeneration
Human	Burgess et al. 2010; [71] Conley et al. 2020 [72]	Melatonin rhythms	~ 25–73% of IBD patients had disrupted melatonin rhythms
	Chakradeo et al. 2018; [73] Swanson et al. 2021 [74]	Variability in sleep timing	Observed more in IBD patients vs. controls (whether inactive or active disease), associated with more severe IBD disease history, more intestinal permeability, more pro-inflammatory gut microbiota
	Chakradeo et al. 2018; [73] Chrobak et al. 2018 [75]	Later chronotype/more eveningness	Associated with reduced IBD-related quality of life, increased fatigue