New study shows that even your fat cells need sleep
In a study that challenges the long-held notion that the primary function of sleep is to give rest to the brain, researchers have found that not getting enough shut-eye has a harmful impact on fat cells, reducing by 30 percent their ability to respond to insulin, a hormone that regulates energy.
Sleep deprivation has long been associated with impaired brain function, causing decreased alertness and reduced cognitive ability. The latest finding—published by University of Chicago Medicine researchers in the Oct. 16 issue of the Annals of Internal Medicine—is the first description of a molecular mechanism directly connecting sleep loss to the disruption of energy regulation in humans, a process that can lead over time to weight gain, diabetes and other health problems. The study suggests that sleep's role in energy metabolism is at least as important as it is in brain function.
"We found that fat cells need sleep to function properly," said study author Matthew Brady, PhD, associate professor of medicine and vice-chair of the Committee on Molecular Metabolism and Nutrition at the University of Chicago.
Brady said body fat plays an important role in humans.
"Many people think of fat as a problem, but it serves a vital function," he said. "Body fat, also known as adipose tissue, stores and releases energy. In storage mode, fat cells remove fatty acids and lipids from the circulation where they can damage other tissues. When fat cells cannot respond effectively to insulin, these lipids leach out into the circulation, leading to serious complications."
Esra Tasali, MD, assistant professor of medicine at the University of Chicago and co-senior author, led the recruitment of six men and one woman, all young, lean and healthy. Each volunteer went through two study conditions, at least four weeks apart. In one, they spent 8.5 hours a night in bed for four consecutive nights. In the other, they spent 4.5 hours in bed for four nights. Food intake, strictly controlled, was identical under both study conditions.
On the morning after the fourth night following both the long and short sleep conditions, each volunteer took an intravenous glucose tolerance test, which measures total-body insulin sensitivity. The researchers performed a biopsy, removing abdominal fat cells from the area near each volunteer's navel. Then they measured how these fat cells responded to insulin.
The researchers assessed insulin sensitivity at the molecular level by measuring the phosphorylation of a protein called Akt within fat cells. Akt phosphorylation is a crucial early chemical step in the cell's response to insulin.
After four nights of short sleep, total-body insulin response decreased by an average of 16 percent. The insulin sensitivity of fat cells decreased by 30 percent. This reduction is comparable to the difference between cells from obese vs. lean participants or from people with diabetes versus non-diabetic controls.
They found that the sleep-deprived study participants had a decreased response to a range of doses of insulin. It took nearly three times as much insulin to provoke half of the maximum Akt response in volunteers who had been deprived of sleep.
"Sleeping four to five hours a night, at least on work days, is now a common behavior" said study author and sleep specialist Esra Tasali.
"Some people claim they can tolerate the cognitive effects of routine sleep deprivation," said co-author Eve Van Cauter, PhD, the Frederick H. Rawson Professor of Medicine and director of the sleep, metabolism and health center at the University of Chicago. "In this small but thorough study, however, we found that seven out of seven subjects had a significant change in insulin sensitivity. They are not tolerating the metabolic consequences."
The study was one of the first to bring together sleep research experts and biologists focused on energy regulation and metabolism in adipose tissue. The impetus came from a sleep-research graduate student, Josiane Broussard, PhD '10, lead author of the study and now a Society in Science-Branco Weiss fellow at Cedars-Sinai Medical Center in Los Angeles. She wanted to combine her interest in sleep and metabolism with research at the molecular level.
So she pulled together a team for this project that included the two sleep researchers, Tasali and Van Cauter, plus two specialists from the University of Chicago Kovler Diabetes Center, David Ehrmann, MD, and Brady, who studies how insulin regulates energy storage in fat and liver cells.
They focused on fat cells because of their direct links to metabolic disruption and weight gain. These cells store energy for the body, are exquisitely sensitive to insulin and help regulate appetite.
Witnessing the direct effect of sleep deprivation on a peripheral tissue such as fat at the cellular level "was an eye-opener," Broussard said. It helps cement the link between sleep and diabetes and "suggests that we could use sleep like diet and exercise to prevent or treat this common disease."
Brady said the study opens up many new questions.
"What signals from sleep loss affect the fat cell? What effect does dysfunctional fat have at the whole-body level?" Brady wondered. "And if we can deprive healthy people of sleep and make them worse, can we take sick people, such as those with the common combination of sleep apnea, obesity and diabetes, improve their sleep and make them better? That's the missing link in the sleep-obesity-diabetes connection."
This study is "a valuable contribution to the understanding of the causal pathways by which reduced sleep duration may directly contribute to diabetes and obesity," according to an editorial in the journal by Francesco Cappuccio, MD, DSc, and Michelle Miller, PhD, of the University of Warwick, in Coventry, United Kingdom. "These results point to a much wider influence of sleep on bodily functions, including metabolism, adipose tissue, cardiovascular function, and possibly more."
More information: The paper, "Impaired Insulin Signaling in Human Adipocyes," appears in the Oct. 16, 2012, issue of the Annals of Internal Medicine.
Journal reference: Annals of Internal Medicine
Provided by University of Chicago Medical Center
- Lack of sleep leads to insulin resistance in teens Sep 29, 2012 | not rated yet | 0
- Weight gain induced by high-fat diet increases active-period sleep and sleep fragmentation Jul 10, 2012 | not rated yet | 0
- One sleepless night can induce insulin resistance in healthy people May 05, 2010 | not rated yet | 0
- Fat kids linked to lack of sleep Oct 19, 2006 | not rated yet | 0
- A good night's sleep may reduce risk of type 2 diabetes in obese teens Sep 20, 2011 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Pressure-volume curve: Elastic Recoil Pressure don't make sense
May 18, 2013 From pressure-volume curve of the lung and chest wall (attached photo), I don't understand why would the elastic recoil pressure of the lung is...
If you became brain-dead, would you want them to pull the plug?
May 17, 2013 I'd want the rest of me to stay alive. Sure it's a lousy way to live but it beats being all-the-way dead. Maybe if I make it 20 years they'll...
MRI bill question
May 15, 2013 Dear PFers, The hospital gave us a $12k bill for one MRI (head with contrast). The people I talked to at the hospital tell me that they do not...
Ratio of Hydrogen of Oxygen in Dessicated Animal Protein
May 13, 2013 As an experiment, for the past few months I've been consuming at least one portion of Jell-O or unflavored Knox gelatin per day. I'm 64, in very...
Alcohol and acetaminophen
May 13, 2013 Edit: sorry for the typo in the title , can't edit I looked around on google quite a bit and it's very hard to find precise information on the...
Marie Curie's leukemia
May 13, 2013 Does anyone know what might be the cause of Marie Curie's cancer
- More from Physics Forums - Medical Sciences
More news stories
Salamanders' immune systems are key to their remarkable ability to regrow limbs, and could also underpin their ability to regenerate spinal cords, brain tissue and even parts of their hearts, scientists have ...
Medical research 9 minutes ago | not rated yet | 0 |
New research from the University of Southampton has shown that blind and visually impaired people have the potential to use echolocation, similar to that used by bats and dolphins, to determine the location of an object.
Medical research 2 hours ago | not rated yet | 1 |
A novel vaccine study from South Dakota State University (SDSU) will headline the groundbreaking research that will be unveiled at the American Association of Pharmaceutical Scientists' (AAPS) National Biotechnology Conference ...
Medical research 3 hours ago | not rated yet | 0
Every 20 seconds, a limb is lost as a consequence of diabetic foot ulcer that does not heal. To date, medical solutions that can change this situation are very limited. In his doctoral thesis Yue Shen from the Industrial ...
Medical research 7 hours ago | 5 / 5 (1) | 0
Researchers have pinpointed a catalytic trigger for the onset of Alzheimer's disease – when the fundamental structure of a protein molecule changes to cause a chain reaction that leads to the death of neurons ...
9 minutes ago | not rated yet | 0 |
Study shows premature birth interrupts vital brain development processes leading to reduced cognitive abilities
Researchers from King's College London have for the first time used a novel form of MRI to identify crucial developmental processes in the brain that are vulnerable to the effects of premature birth. This new study, published ...
8 minutes ago | not rated yet | 0 |
Whooping cough has exploded in the United States and some other developed countries in recent decades, and many experts suspect ineffective childhood vaccines for the alarming resurgence.
8 minutes ago | not rated yet | 0 |
(HealthDay)—For young adults needing either a chest or abdominopelvic computed tomography (CT), the short-term risk of death from underlying morbidity is greater than the long-term risk of radiation-induced ...
49 minutes ago | not rated yet | 0
New research suggests that for some hospitalized ICU patients on mechanical ventilators, using headphones to listen to their favorite types of music could lower anxiety and reduce their need for sedative medications.
1 hour ago | not rated yet | 0 |
Over the past few decades, neuroscientists have made much progress in mapping the brain by deciphering the functions of individual neurons that perform very specific tasks, such as recognizing the location ...
5 hours ago | 5 / 5 (5) | 0 |