The researchers found that nicotine weakens the sleep-inducing effects of alcohol.
Image credit: MU Health
At least 85% of adults in the US who are alcohol-dependent are also dependent on nicotine, say researchers from the University of Missouri (MU) School of Medicine in Columbia, who report their findings in the Journal of Neurochemistry.
They hope their study will lead to improvements in the health not only of heavy drinkers and smokers, but also of people with mental illnesses such as schizophrenia, which often is associated with smoking.
Lead author Mahesh Thakkar, associate professor and director of research in the MU School of Medicine's Department of Neurology, says:
"We have found that nicotine weakens the sleep-inducing effects of alcohol by stimulating a response in an area of the brain known as the basal forebrain."
In previous work, the team found that nicotine acts via the wake-promoting basal forebrain to increase alcohol consumption and stimulate the brain's pleasure center - the nucleus accumbens.
Nicotine acts through the forebrain to suppress alcoholic sleepiness
In the new study, the researchers fit four groups of rats with sleep-recording equipment. Each group was then treated with one of four combinations: alcohol and nicotine, alcohol and no nicotine (dummy dose used), water and nicotine, or water and no nicotine. The nicotine dose was injected into the forebrain; the alcohol or water was instilled into the stomach.
The results showed that while rats exposed to alcohol displayed strong sleep promotion, those exposed to nicotine showed less alcohol-induced sleepiness.
The researchers say the findings show that, through its effect on the forebrain, nicotine suppresses the sleep-inducing effects of alcohol.
Prof. Thakkar concludes:
"One of the adverse effects of drinking alcohol is sleepiness. However, when used in conjunction with alcohol, nicotine acts as a stimulant to ward off sleep. If an individual smokes, then he or she is much more likely to consume more alcohol, and vice-versa. They feed off one another."
He says identifying the reactions that take place when people smoke and drink may help to find ways of curbing alcohol and nicotine addiction.
According to the World Health Organization (WHO), Europe has the highest levels of tobacco and alcohol consumption in the world. A recent report on the region's health finds that while there is heartening progress, due to "alarming" rates of smoking, alcohol use and obesity, the next generation of Europeans may not live as long as their grandparents.
Meanwhile, Medical News Today recently learned that cigarette smoking and heavy alcohol use cause epigenetic changes to DNA that reflect accelerated biological aging in distinct, measurable ways. Researchers found that while all levels of exposure to smoke were linked to significantly premature aging, moderate alcohol use - about one to two drinks per day - was associated with the healthiest aging, while very low and high consumption were linked to accelerated aging.