Chronic alcohol consumption can adversely affect body's biological clock's ability to synchronize daily activities to light, according to a new study on hamsters.
It continues to affect the body's clock (circadian rhythm), even days after the drinking ends.
The researchers from Kent State University and the University of Tennessee have shown that alcohol consumption affects the master clock, located in the suprachiasmatic nucleus (SCN) section of the brain.
This clock controls the circadian cycle, a roughly 24-hour cycle, which regulates sleeping and waking, as well as the timing of a variety of other physiological functions, such as hormonal secretions, appetite, digestion, activity levels and body temperature.
Disruption of the clock dramatically increases the risks of developing cancer, heart disease, and depression, among other health problems.
In the new study, the researchers used hamsters to find out how alcohol affects circadian rhythms. The control group received water only. A second group received water containing 10pct alcohol and the third group received water containing 20pct alcohol.
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The hamsters that drank alcohol had the hardest time shifting their rhythms after exposure to the dim light.
The more alcohol they drank, the harder it was to adjust.
Exposure to dim light caused the water-only hamsters to wake up 72 minutes earlier than they normally would. The 10pct alcohol group woke up 30 minutes earlier and the 20pct alcohol group woke up only 18 minutes earlier.
The hamsters that consumed alcohol had fewer bouts of activity that lasted longer than the water-consuming controls.
Chronic drinking continues to affect the biological clock even after withdrawal from alcohol.
The researchers aim to apply the research to people, who also show circadian disruptions from drinking.
It suggests that people who drink alcohol, particularly late into the night, may not respond to important light cues to keep their biological clocks in synch with daylight over the next 24 hours. Even low levels of alcohol may impair the response to light cues.
After the first 24 hours, the circadian cycle continues to be affected, even without further consumption of alcohol.
The findings appear in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology.
