Study: Alcohol affects circadian rhythms

Chronic alcohol consumption blunts the ability of the body’s biological clock to synchronize daily activities to light, U.S. researchers said.

Christina L. Ruby, Allison J. Brager, Marc A. DePaul and J. David Glass, all of Kent State University, and Rebecca A. Prosser of the University of Tennessee, said disruption of the circadian rhythms dramatically increases the risks of developing cancer, heart disease and depression.

The researchers divided hamsters into three groups, differing only in what they drank. The control group received water only, a second group received water containing 10 percent alcohol and the last third received water containing 20 percent alcohol.

If given a choice, hamsters prefer alcohol, the researchers said.

The animals drank as much as they wanted and lived in an environment that provided 14 hours of light and 10 hours of darkness each day. The researchers also changed the amount and intensity of light.

The researchers said the hamsters that drank alcohol had the hardest time shifting their rhythms after exposure to dim light, and the more alcohol they drank, the harder it was to adjust.

The findings are published in the American Journal of Physiology — Regulatory, Integrative and Comparative Physiology.