"There is a strong relationship between alcohol and sleep," said Dwayne Godwin, Ph.D., senior researcher. "Many people have sleep problems when they stop drinking. If we could stabilize sleep, or take it back to a normal rhythm, it would address one of the reasons that alcoholics go back to drinking."
Godwin and colleagues studied the relationship between sleep and alcohol in monkeys. They found that in animals that chronically drank alcohol, the brain attempts to increase a particular protein associated with brain waves that are important to normal sleep. The finding suggests that new medications to target the protein might improve sleep in chronic alcohol users.
"If we can find a way to solve the problem of sleep disturbance, it could possibly affect the outcome of addiction treatment," said Godwin.
Previous research in animals and humans has shown that alcohol initially acts as a sedative in casual drinkers, making it easier to sleep. But in the second half of the night, sleep is often disrupted. In chronic alcohol users, the brain develops a tolerance to the sedative effects of alcohol and there is an increase in light sleep and a decrease in restorative sleep. This may prompt alcohol users to increase their consumption to try to improve sleep. One study revealed that 44 percent to 60 percent of alcohol patients used alcohol to help them sleep.
Godwin said the brain adapts to long-term alcohol use and doesn't immediately return to normal when alcohol use is stopped. It may take months for the brain to revert to normal sleep patterns, or it may never return to a truly normal state. In the meantime, sleep problems can get worse. Insomnia has been shown to occur in 36 percent to 72 percent of alcoholic patients during both active drinking and withdrawal.
"There is a significant relationship between alcoholics returning to consumption because of this sleep issue," said Godwin, an associate professor of neurobiology and anatomy. "One reason they may go back to drinking may be an attempt to make their sleep feel more normal or satisfying."
Previous research has shown that alcohol affects spindle waves, which are brain rhythms associated with normal sleep. The primary generators of spindle waves are proteins called calcium channels that are involved with cell communication. These channels may also help to set the phase of sleep.
Chronic alcohol consumption has been shown to disturb the function of calcium channels in the thalamus, a brain region involved in sleep. In the current study, Godwin and colleagues found that animals that self-administered alcohol had a fourfold increase in one of the genes that express the calcium channels, compared to animals that didn't consume alcohol.
"The alcohol suppresses the calcium channels, so the cells in the thalamus may compensate by making more copies of the gene," said Godwin. "However, this overproduction of the gene did not lead to an increase in functional calcium channels and the cells still had disturbances in the channels, so the animals as a group tended to have disrupted sleep."
Godwin and colleagues plan to continue the work to learn how alcohol disrupts the protein. Does it reduce the number of calcium channels? Or does it cause the channels to malfunction? Knowing more about how the channels respond to alcohol could lead to drugs that could target the calcium channels and address sleep problems associated with alcohol.
Other researchers involved in the project were Brian K. Nordskog, Ph.D., William B. Carden, Ph.D., Georgia M. Alexander, Brian McCool, Ph.D., James Daunais, Ph.D., David Friedman, Ph.D., and Kathleen Grant, Ph.D., all from Wake Forest Baptist.
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