TLR4 and insomnia: Moreover, research has shown that the SCFAs increased through microbial metabolism of sour SZR can modulate the expression of representative factors in the TLR4/NF-κB/NLRP3-related signaling pathway in the colon, thereby regulating the microbiota-gut-brain axis and improving insomnia and depressive behaviors in mice (Du et al., 2023; Hua et al., 2021).