Alcohol interferes with sleep, but not by disrupting the circadian clock

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A drink before bed? Around 50 million adults in the US take a drink to help them fall asleep, but that drink is being advised against by researchers at the University of Missouri School of Medicine. Their research has found that alcohol actually disrupts sleep–even if it causes people to nod off. It disrupts sleep differently from what is commonly believed, however. Rather than the circadian rhythm, alcohol actually affects the body’s homeostatic system.

“Based on our results, it’s clear that alcohol should not be used as a sleep aid,” Dr. Pradeep Sahota, chair of the MU School of Medicine’s Department of Neurology and an author of the study, said in the press release.

Around one-third of our people’s lives are spent sleeping, and around 20 percent of America’s 250 million adults use alcohol. This is relevant to the nation’s health and economy, the researchers pointed out. They cited research that has found alcohol-related sleep disorders cost the US  at least $18 billion per year.

The MU team have spent five years studying the interaction between sleep and alcohol, and have concluded in their most recent report that alcohol disturbs sleep, but in a way that may surprise scientists and readers alike.

“The prevailing thought was that alcohol promotes sleep by changing a person’s circadian rhythm–the body’s built-in 24-hour clock,” said Dr Mahesh Thakkar, another author of the study. “However, 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.”

The body has two systems that both play a role in sleep. The homeostatic system builds up pressure to sleep the longer a person stays awake, and the circadian system is an internal clock regulated by the body’s perception of light and dark.

A person might drink a lot of coffee and power through a night without sleeping. In the morning they would feel increased pressure to sleep from their homeostatic system, but their circadian clock would tell them it was time to be awake.

Alcohol does something of the opposite, the researchers found. It promotes sleepiness through the homeostatic system while leaving the circadian rhythm unaffected. While a person may nod off more quickly, it will be likely that they will not sleep through the whole night.

“Alcohol disrupts sleep and the quality of sleep is diminished. Additionally, alcohol is a diuretic, which increases your need to go the bathroom and causes you to wake up earlier in the morning,” Sahota pointed out.

The researchers advised other options that could be pursued by people having difficulty getting a good night’s rest.

“If you are experiencing difficulty sleeping, don’t use alcohol,”said Thakkar. “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 report, “Alcohol Disrupts Sleep Homeostasis,” was completed by Drs Mahesh Thakkar, Pradeep Sahota and Rishi Sharma, and was published in the international biomedical journal Alcohol.

By Cheryl Bretton