Alcohol interferes with body's ability to regulate sleep

At right: Mahesh Thakkar, PhD, associate professor and director of research in the MU School of Medicine’s Department of Neurology, and Pradeep Sahota, MD, chair of the MU School of Medicine’s Department of Neurology, have studied alcohol’s effects on sleep for more than five years. Their study found that drinking interferes with the brain’s built-in system for regulating a person’s need for sleep. Credit: Image courtesy of University of Missouri-Columbia

Researchers from the University of Missouri School of Medicine have found that drinking alcohol to fall asleep interferes with sleep homeostasis, the body's sleep-regulating mechanism.

Alcohol is known to be a powerful somnogen, or sleep inducer, and approximately 20 percent of the U.S. adult population drinks alcohol to help fall asleep. The researchers, led by Mahesh Thakkar, PhD, associate professor and director of research in the MU School of Medicine's Department of Neurology, have studied alcohol's effects on sleep for more than five years. They found that alcohol interferes with the brain's built-in system for regulating a person's need for sleep.

"The prevailing thought was that alcohol promotes sleep by changing a person's circadian rhythm -- the body's built-in 24-hour clock," Thakkar said. "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."

Sleep homeostasis balances the body's need for sleep in relation to how long a person has been awake. If an individual loses sleep, the body produces adenosine, a naturally occurring sleep-regulating substance that increases a person's need for sleep. When a person goes to sleep early, sleep homeostasis is shifted and he or she may wake up in the middle of the night or early morning. The researchers found that alcohol alters the sleep homeostatic mechanism and puts pressure on an individual to sleep. When this happens, the sleep period is shifted, and a person may experience disrupted sleep.

"Based on our results, it's clear that alcohol should not be used as a sleep aid," said Pradeep Sahota, MD, chair of the MU School of Medicine's Department of Neurology and an author of the study. "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."

In addition to studying alcohol's impact on sleep homeostasis, the researchers explored how alcohol withdrawal affects sleep. The investigators found that after extended periods of frequent drinking, subjects would fall asleep as expected, but would wake within a few hours and would be unable to fall back asleep. When the subjects were not given alcohol, the researchers found that subjects showed symptomatic insomnia.

"During acute alcohol withdrawal, subjects displayed a significant increase in wakefulness with a reduction in rapid eye movement and non-rapid eye movement sleep," Thakkar said. "This caused insomnia-like symptoms and suggests an impaired sleep homeostasis."

The researchers hope to use these findings to explore other effects of alcohol consumption.

"Sleep is an immense area of study," Thakkar said. "Approximately one-third of our life is spent sleeping. Coupled with statistics that show 20 percent of people drink alcohol to sleep, it's vital that we understand how the two interact. If you are experiencing difficulty sleeping, don't use alcohol. 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 study, "Alcohol Disrupts Sleep Homeostasis," is an invited article published in the international biomedical journal Alcohol.

Source:  University of Missouri-Columbia

Artificial light, biological clock disruptions, increase breast cancer risk, study finds

Employment as a flight attendant has been found to be related to an increased risk of breast cancer. Credit: © dmitrimaruta / Fotolia

The disruption of a person's circadian rhythm -- their 24-hour biological clock -- has been linked to an increased risk of breast cancer, according to new University of Georgia research. The culprit, in this study in particular, is artificial light.

"Exposure to artificial light leads to a significantly higher risk for developing breast cancer," said Chunla He, a biostatistics graduate student in the UGA College of Public Health. "To decrease the use of artificial light, people should avoid working at night and implement earlier bed times."

Her research, published in the International Archives of Occupational and Environmental Health, examined key studies that included risk factors for developing breast cancer.

"A large body of related research about circadian rhythms and breast cancer exists," He said. 

"However, these studies are inconsistent and have a variety of limitations."

Under the mentorship of Sara Wagner Robb, assistant professor of epidemiology in the College of Public Health, He turned to previous studies to see what the research revealed.

In addition to other relevant exposures, He examined studies on breast cancer and flight attendants, who typically work both day and night shifts. The flight attendants represented a group of workers particularly susceptible to disrupted circadian rhythms, which are heavily influenced by light.

In her analysis, He found that employment as a flight attendant was related to an increased risk of breast cancer.

"People naturally secrete the hormone melatonin, which helps to regulate the circadian rhythm," He said. "When the sleep-wake cycle is disrupted by artificial light, melatonin secretion is adversely affected."

Robb recommends spreading this information to shift workers so they understand the harms in disrupting their circadian rhythms.

"Individuals engaging in this type of work should be aware of these risks and may make efforts to adjust their circadian rhythms," she said. "Although additional studies are certainly needed, scientists are becoming increasingly aware of the health risks associated with night workers and others exposed to circadian-disrupting behaviors."

Robb and He also advise that future research needs to examine social constraints -- which may foster disruption of circadian rhythms -- on shift workers. Additionally, shift workers should contact their primary care physicians for personalized treatment and options.

"This information tells us the harm in disrupting our natural cycle," He said. "With this new analysis, we must be cautious in our exposure to artificial light."

The article was co-authored by Sonia Taj Anand, a former graduate student in the College of Public Health; Mark H. Ebell, professor of epidemiology; and John E. Vena, Medical University of South Carolina.

Source: University of Georgia