In a presentation at the Research Society on Alcoholism in San Francisco, Dwayne W. Godwin, Ph.D. explained that a key brain region involved in sleep, the thalamus, is "exquisitely sensitive to alcohol."
The cells in the thalamus possess an ion channel that behaves differently depending on the amount of alcohol that has been drunk. "Low doses of alcohol increase activity; high doses shut it down," said Godwin, associate professor of neurobiology and anatomy.
Characteristic "spindle" brain waves are produced during what is called stage II sleep, which is transiently enhanced after alcohol consumption but is reduced later in the night . The spindle waves are generated in the thalamus and picked up in brain wave recordings.
Godwin and colleagues Breck Carden, Ph.D., Jian Mu, M.D., and Nuwan Kurukulasuriya, Ph.D. in the Center for the Neurobehavioral Study of Alcohol are using the ferret as an animal model for sleep. The ferret thalamus produces the same characteristic spindle waves during stage II sleep as in people and reacts differently depending on the amount of alcohol.
"Despite widespread interest in the influence of alcohol on sleep, the influence of alcohol on the thalamus had been uncharted territory," he said. Use of the ferret thalamus "is optimal for exploring such mechanisms, because they possess all of the necessary circuitry for the generation of spindle waves, which allows us to translate our studies to the situation in humans."
Godwin said human studies have shown that just one drink before bed may decrease the time it takes to fall asleep. But in the second half of the night, sleep often is disrupted. "You may tend to wake up more and be a little more restless."