Around 20% of adult Americans use alcohol - known to be a powerful sleep inducer - to help them fall asleep. However, new research shows that while alcohol may bring on sleepiness, it can disrupt sleep and, over time, cause insomnia by interfering with the body's system for regulating sleep.
Researchers from the University of Missouri (MU) School of Medicine in Columbia, MO, report their findings in the journal Alcohol. They have been studying the relationship between alcohol consumption and sleep for over 5 years.
Lead researcher Mahesh Thakkar, associate professor and director of research in MU School of Medicine's Department of Neurology, says the prevailing view is that alcohol induces sleep by altering circadian rhythm - the body's 24-hour clock:
"However," he adds, "we discovered that alcohol actually promotes sleep by affecting a person's sleep homeostasis - the brain's built-in mechanism that regulates your sleepiness and wakefulness."
Sleep homeostasis is how the body balances a person's need for sleep according to how long they have been awake. To do this, it uses adenosine, a chemical produced naturally in cells.
The level of adenosine outside of cells goes up during prolonged periods of wakefulness and goes down again during sleep. When the extracellular adenosine level goes up, it blocks the wake-promoting cells in the basal forebrain. When it goes down again, the block is lifted, and the wake-promoting cells become active.
Thus, if a person goes to sleep earlier than usual, the resulting shift in sleep homeostasis may cause them to wake up in the middle of the night or very early in the morning.
Alcohol causes shift in sleep homeostasis by boosting adenosine
The researchers carried out a series of experiments with mice and rats to study what happens to adenosine in the brain when alcohol is present.
They found that alcohol boosts extracellular levels of adenosine, which in turn induces sleep by blocking the wake-promoting cells of the basal forebrain.
Co-author Dr. Pradeep Sahota, chair of MU School of Medicine's Department of Neurology, says based on these results, "it's clear that alcohol should not be used as a sleep aid:"
"Alcohol disrupts sleep and the quality of sleep is diminished," he adds, "Additionally, alcohol is a diuretic, which increases your need to go the bathroom and causes you to wake up earlier in the morning."
In another part of the study, the researchers also investigated the effect of alcohol withdrawal on sleep. They found after extended periods of binge-drinking, sleep came quickly as expected, but within a few hours, wakefulness set in, preventing a return to sleep.
Also, when alcohol was withdrawn, insomnia set in, as Prof. Thakkar explains:
"During acute alcohol withdrawal, subjects displayed a significant increase in wakefulness with a reduction in rapid eye movement and non-rapid eye movement sleep. This caused insomnia-like symptoms and suggests an impaired sleep homeostasis."
The team now plans to take their studies further and explore other effects of alcohol consumption.
'Alcohol not a good way to solve sleep problems'
Prof. Thakkar says we spend around a third of our lives sleeping. Add to that the fact around 20% of people drink alcohol to get to sleep, "it's vital that we understand how the two interact."
He also urges people not to use alcohol to solve their sleep problems:
"Talk to your doctor or a sleep medicine physician to determine what factors are keeping you from sleeping. These factors can then be addressed with individualized treatments."
The researchers note in their background information that in the US, the "societal costs of alcohol-related sleep disorders exceed $18 billion."
Grants from the National Institute of Alcohol Abuse and Alcoholism and resources from the Harry S. Truman Memorial Veterans' Hospital helped fund and support the study.
Meanwhile, Medical News Today recently learned of another new study that suggests altered sleep-wake protein is linked to cancer. There, researchers found that hPer2 - a protein that regulates circadian rhythm - also protects against cancer, and that disrupting circadian rhythm alters the function of hPer2 and may lead to cancer development.