Disrupted Sleep-Wake Cycles May Worsen Alcohol-Induced Organ Damage

Alcohol consumption can cause damage to multiple organs, particularly the liver and intestinal tract. High levels of alcohol intake are linked to conditions such as liver cirrhosis, i.e., severe scarring of liver tissue, and intestinal inflammation. However, the extent of alcohol-induced organ damage varies widely across patients and may not be determined by alcohol intake alone. The risks of alcohol-related organ injuries may be increased, e.g., by disruptions of the circadian rhythm—the natural daily sleep-wake cycle. Many physiological processes depend on the circadian rhythm, for example, digestion and body temperature, and, on the molecular level, the expression of genes linked with, e.g., tissue repair and inflammation.

Faraz Bishehsari, Rush University Medical Center, Chicago, IL, USA, University of Texas, Houston, USA, and colleagues have studied the connection between alcohol intake, the disruption of the circadian rhythm, and key cellular processes in an experimental mouse model. Mice were fed diets with or without alcohol while being held in two different light/dark conditions: a regular cycle of light/dark conditions (12 hours light, 12 hours dark) or a shifting light/dark-cycle with 12 h of light alternating between daytime and nighttime every week. The scientists then studied the expression of specific sets of genes linked to the circadian rhythm, so-called circadian clock genes (CoClGs), as well as genes connected to alcohol-induced intestinal and liver damage.

By comparing gene expression in the mice living under different dietary and light/dark conditions, the researchers found that alcohol intake alone dysregulated the expression of CoCIGs. Moreover, alcohol intake combined with a disrupted sleep-wake cycle significantly intensified this effect. The expression of genes associated with alcohol-induced intestinal and liver damage was also disrupted notably by the combined effects of alcohol intake and disrupted sleep-wake cycle. This work indicates that a disrupted sleep-wake cycle may intensify the harmful effects of alcohol by affecting physiological processes involved in alcohol-induced organ damage.