Poor Sleep Fuels Colorectal Cancer Growth Through a Gut Bacteria-Bile Acid Chain

Chronic sleep loss may be doing far more damage than impairing your focus or mood. A study published in June 2025 by Chen and colleagues found that sleep deprivation significantly increased tumor burden and malignancy frequency in mice predisposed to colorectal cancer, and traced the mechanism through a specific chain: disrupted gut bacteria, a surge in a bile acid called taurocholic acid, and activation of a well-known cancer growth pathway. The findings are preliminary and come entirely from animal models, but they sketch a plausible molecular route connecting a common lifestyle habit to one of the world's most lethal cancers.

Sleep Deprivation Accelerates Tumor Growth in CRC-Prone Mice

The researchers used male ApcMin/+ mice, a widely used genetic model for colorectal tumor research that develops intestinal tumors spontaneously through a mutation in the Apc tumor-suppressor gene. Eight-week-old mice were divided into a sleep-deprived group and a sleep-control group and followed for 12 weeks. The sleep-deprivation protocol ran in cycles of 24 hours of enforced wakefulness followed by 48 hours of recovery, designed to mirror the pattern of chronic intermittent sleep loss rather than a single all-nighter.

By the end of the trial, sleep-deprived mice showed meaningfully higher tumor burden and a greater proportion of malignant lesions compared to controls. Intestinal tissue from sleep-deprived animals also showed increased crypt depth, more Ki67-positive proliferating cells, and higher PCNA expression, all signs that gut epithelial cells were dividing more rapidly. At the same time, goblet cell numbers dropped, and the barrier proteins E-cadherin and ZO-1 declined, meaning the gut lining itself had become more permeable and more inflamed. Pro-inflammatory cytokines including TNF-alpha, IL-17A, IL-1 beta, and IL-6 rose, while the anti-inflammatory cytokines IL-10 and IL-22 fell.

How the Gut Microbiome Shifts After Chronic Sleep Loss

Sleep disorders have been linked to colorectal cancer risk in human populations through several proposed mechanisms, including metabolic disruption and microbiome changes. This study drills into the microbiome angle with 16S rRNA gene sequencing of fecal samples. Sleep-deprived mice showed a clear separation in microbial community composition from controls. At the phylum level, Bacteroidetes increased substantially. More striking was what disappeared: Lactobacillus, Allobaculum, Bifidobacterium, and Monoglobus were all significantly depleted.

Lactobacillus carried the highest discriminative power in the analysis, meaning it was the single genus that most reliably told the two groups apart. The researchers note that Lactobacillus populations are known to fluctuate with circadian rhythms, raising the hypothesis that disrupting the sleep-wake cycle knocks its populations out of their normal daily cycle.

Computational pathway prediction also suggested a reduction in choloylglycine hydrolase activity in the sleep-deprived microbiomes, an enzyme that bacteria use to process bile acids. That clue pointed toward the metabolomics data.

Taurocholic Acid Links Microbiome Disruption to Cancer Signaling

Untargeted LC-MS/MS metabolomics of fecal samples identified 260 differentially abundant metabolites between the two groups: 83 were higher in sleep-deprived mice and 177 were lower. The most prominent upregulated metabolite was taurocholic acid (TCA), a primary bile acid conjugate that was subsequently confirmed by ELISA. Spearman correlation analysis showed that TCA levels were strongly and negatively correlated with Lactobacillus abundance, consistent with the idea that losing Lactobacillus (which normally helps deconjugate bile acids) allows TCA to accumulate.

Gut microbiome dysregulation can activate pro-inflammatory signaling pathways that drive colorectal cancer progression, and TCA appears to be one metabolic node where that happens here. When the team applied TCA to human CRC cell lines (HCT116 and SW480), they observed increased cell viability, proliferation, migration, and invasion. In a subcutaneous xenograft model in nude mice, exogenous TCA significantly accelerated tumor growth, increasing both tumor volume and weight.

RNA sequencing of TCA-treated cells revealed 694 significantly altered genes. The MAPK signaling pathway showed the highest gene ratio among enriched pathways. Western blot confirmed a marked rise in phosphorylated ERK (p-ERK), the active form of a kinase central to cell proliferation. Blocking ERK with the inhibitor SCH772984 abolished TCA-induced gains in proliferation, migration, and invasion, confirming the pathway was not just correlated with the effect but required for it.

The team then traced one step further upstream. RasGRF1, a guanine nucleotide exchange factor that activates the Ras-MAPK cascade, was significantly elevated in TCA-treated cells at both the mRNA and protein levels. Silencing RasGRF1 with shRNA reduced ERK phosphorylation in TCA-treated cells, placing it upstream of ERK and confirming the sequence: TCA elevates RasGRF1, RasGRF1 activates ERK, ERK drives tumor cell behavior.

What the Study Cannot Yet Confirm

Several important caveats sit around these findings. The endogenous rise in TCA seen in sleep-deprived mice was modest, while the exogenous TCA concentrations used in cell and xenograft experiments were higher, meaning the in vitro effects may exceed what occurs naturally in a sleep-deprived gut. All experiments used mouse models, which may not fully reflect the heterogeneity of human colorectal cancer. Critically, it remains unknown whether sleep-deprived people or CRC patients with poor sleep quality show comparable TCA elevations.

The modified multiple-platform sleep deprivation method can also introduce stress beyond sleep loss itself, and the authors acknowledge that stress-related physiology may have contributed to some of the observed changes. The direct link between Lactobacillus depletion and TCA accumulation is correlational; functional experiments proving that restoring Lactobacillus would normalize TCA and reduce tumor burden have not yet been done. Nor has ERK inhibition combined with TCA manipulation been tested in a live animal, which would more directly validate the proposed pathway.

What Comes Next for Sleep, Bile Acids, and Colorectal Cancer

Sleep deprivation's role in cancer outcomes extends beyond tumor initiation, with some research suggesting it can also blunt chemotherapy efficacy, making the question of how to interrupt this axis clinically relevant. The findings here suggest several possible intervention points: restoring Lactobacillus through probiotics, reducing bile acid accumulation pharmacologically, or targeting the RasGRF1-ERK node directly.

Colorectal cancer remains a massive global health problem, ranking as the third most common cancer worldwide and projected to reach 3.2 million new cases annually by 2040. If sleep quality proves to be a modifiable factor that influences tumor microenvironment through the gut-bile acid-MAPK axis, even modest preventive benefit would carry significant population-level weight. For now, the chain of evidence runs: chronic sleep loss, Lactobacillus depletion, taurocholic acid accumulation, RasGRF1 activation, ERK phosphorylation, and faster tumor growth. Each link is supported by data; whether the full chain operates in sleeping humans the way it does in insomniac mice remains the central unanswered question.

Evidence rating

INVESTIGATIONAL — 78/100

Caveats:

• All experiments were conducted in mice; whether the same gut microbiota and metabolite changes occur in sleep-deprived humans is unknown.
• Mouse groups contained only 6 animals each, limiting statistical power.
• The sleep deprivation protocol (24-h deprivation / 48-h recovery on platforms) may introduce physical stress beyond sleep loss alone, which could independently affect the microbiome and tumor biology.
• TCA concentrations used in cell and xenograft experiments were higher than the modest elevations observed in sleep-deprived mice, so direct relevance of the dose is uncertain.
• The causal link between Lactobacillus depletion and TCA accumulation was not directly demonstrated — it remains a correlative association requiring functional validation.
• Funding was not disclosed by the authors.

Preclinical study using ApcMin/+ mice (n=6 per group) and CRC cell lines. Demonstrates an association between chronic sleep deprivation, gut microbiota disruption, and elevated taurocholic acid, with mechanistic evidence implicating the MAPK/ERK pathway derived from transcriptomic and pharmacological experiments in vitro and in xenograft models. Causality between specific microbial changes and metabolite accumulation was not directly established, and findings have not been replicated in human populations or independent animal cohorts.

References

1. Jia Chen, Rishun Su, Yong Kuang, et al. (2026). Sleep Deprivation Promotes Colorectal Cancer in Apc ^Min/+ Mice Associated with Modulation of Gut Microbiota and Related Metabolites. International Journal of Biological Sciences. https://doi.org/10.7150/ijbs.134241
2. Junze Ren, Hua Sui, Fanfu Fang, Qi Li, Bai Li (2019). The application of ApcMin/+ mouse model in colorectal tumor researches. Journal of Cancer Research and Clinical Oncology. https://doi.org/10.1007/s00432-019-02883-6
3. Jiahua Liu, Qihang Yuan, Yao Zhang, et al. (2025). Sleep health: an unappreciated key player in colorectal cancer. Journal of Cancer. https://doi.org/10.7150/jca.107117
4. The role of gut microbiome in colorectal cancer development: a comprehensive analysis based on metabolomics and immunomodulatory mechanisms – Frontiers. frontiersin.org. https://www.frontiersin.org/articles/10.3389/fimmu.2023.1258694/full
5. Chronic Sleep Deprivation Negatively Impacts the Gut Microbiota and is Associated with Enhanced Colorectal Cancer Progression and Loss of Chemotherapy Efficacy – UF Health Cancer Institute – University of Florida. cancer.ufl.edu. https://cancer.ufl.edu/education/conference-speakers/chronic-sleep-deprivation-negatively-impacts-the-gut-microbiota-and-is-associated-with-enhanced-colorectal-cancer-progression-and-loss-of-chemotherapy-efficacy/
6. Cailu Shen, Caier Cai, Ying Zhang, et al. (2026). Global burden of colorectal cancer and associated risk factors in young-older adults: Trends from 1990 to 2021 with projections to 2050. Medicine. https://doi.org/10.1097/md.0000000000047448