Lack Of Deep Sleep May Increase Risk Of Type 2 Diabetes

Suppression of slow-wave sleep in healthy young adults significantly decreases their ability to regulate blood-sugar levels and increases the risk of type 2 diabetes, report researchers at the University of Chicago Medical Center.

Credit: iStockphoto/Libby Chapman

Suppression of slow-wave sleep in healthy young adults significantly decreases their ability to regulate blood-sugar levels and increases the risk of type 2 diabetes, report researchers at the University of Chicago Medical Center.

Deep sleep, also called "slow-wave sleep," is thought to be the most restorative sleep stage, but its significance for physical well-being has not been demonstrated. This study found that after only three nights of selective slow-wave sleep suppression, young healthy subjects became less sensitive to insulin. Although they needed more insulin to dispose of the same amount of glucose, their insulin secretion did not increase to compensate for the reduced sensitivity, resulting in reduced tolerance to glucose and increased risk for type 2 diabetes. The decrease in insulin sensitivity was comparable to that caused by gaining 20 to 30 pounds.

Previous studies have demonstrated that reduced sleep quantity can impair glucose metabolism and appetite regulation resulting in increased risk of obesity and diabetes. This current study provides the first evidence linking poor sleep quality to increased diabetes risk.

"These findings demonstrate a clear role for slow-wave sleep in maintaining normal glucose control," said the study's lead author, Esra Tasali, MD, assistant professor of medicine at the University of Chicago Medical Center. "A profound decrease in slow-wave sleep had an immediate and significant adverse effect on insulin sensitivity and glucose tolerance."

"Since reduced amounts of deep sleep are typical of aging and of common obesity-related sleep disorders, such as obstructive sleep apnea these results suggest that strategies to improve sleep quality, as well as quantity, may help to prevent or delay the onset of type 2 diabetes in populations at risk," said Eve Van Cauter, PhD, professor of medicine at the University of Chicago and senior author of the study.

The researchers studied nine lean, healthy volunteers, five men and four women between the ages of 20 and 31. The subjects spent two consecutive nights in the sleep laboratory, where they went to bed at 11 P.M., slept undisturbed but carefully monitored, and got out of bed 8.5 hours later, at 7:30 A.M.

The same subjects were also studied for three consecutive nights during which they followed identical nighttime routines. During this session, however, when their brain waves indicated that they were drifting into slow-wave sleep they were subtly disturbed by sounds administered through speakers beside the bed.

These sounds were loud enough to disrupt deep sleep but not so loud as to cause a full awakening. This technique enabled the researchers to decrease slow-wave sleep by about 90 percent, shifting the subjects from the onset of deep sleep (stage 3 or 4) to a lighter sleep (stage 2) without altering total sleep time.

"Our system proved quite effective," Tasali said. When asked about the sounds the next morning, study subjects vaguely recalled hearing a noise "three or four times," during the night. Some recalled as many as 10 to 15. On average, however, subjects required about 250-300 interventions each night, fewer the first night but more on subsequent nights as "slow-wave pressure," the body's need for deep sleep, accumulated night after night.

"This decrease in slow-wave sleep resembles the changes in sleep patterns caused by 40 years of aging," Tasali said. Young adults spend 80 to 100 minutes per night in slow-wave sleep, while people over age 60 generally have less than 20 minutes. "In this experiment," she said, "we gave people in their 20s the sleep of those in their 60s."

At the end of each study, the researchers gave intravenous glucose (a sugar solution) to each subject, then took blood samples every few minutes to measure the levels of glucose and insulin, the hormone that controls glucose uptake.

They found that when slow-wave sleep was suppressed for only three nights, young healthy subjects became about 25 percent less sensitive to insulin. As insulin sensitivity decreased, subjects needed more insulin to dispose of the same amount of glucose. But for eight of the nine subjects, insulin secretion did not go up to compensate for reduced effects. The result was a 23 percent increase in blood-glucose levels, comparable to older adults with impaired glucose tolerance.

Those with low baseline levels of slow-wave sleep had the lowest levels after having their sleep patterns disrupted and the greatest decrease in insulin sensitivity.

The alarming rise in the prevalence of type 2 diabetes is generally attributed to the epidemic of obesity combined with the aging of the population. "Previous studies from our lab have demonstrated many connections between chronic, partial, sleep deprivation, changes in appetite, metabolic abnormalities, obesity, and diabetes risk," said Van Cauter. "These results solidify those links and add a new wrinkle, the role of poor sleep quality, which is also associated with aging."

"Chronic shallow non-REM sleep, decreased insulin sensitivity and elevated diabetes risk are typical of aging," the authors conclude. "Our findings raise the question of whether age-related changes in sleep quality contribute to the development of these metabolic alterations."

This research was reported in the "Early Edition" of the Proceedings of the National Academy of Science, available online Dec. 31, 2007.

The National Institutes of Health funded this research. Additional authors include Rachel Leproult and David Ehrmann of the University of Chicago Medical Center.

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Story Source:

The above story is based on materials provided by University of Chicago Medical Center. Note: Materials may be edited for content and length.

Robb Wolf Discusses The Paleo Solution (Part 2)

Here's the second video of Robb Wolf discussing the health benefits of the Paleo Diet.

Robb Wolf Discusses The Paleo Solution (Part 1)

This is the first video in a series of interviews with Robb Wolf discussing the fundamental principles of the Paleo Diet.

If you've got an interest in weight loss and preventative medicine, you'll really enjoy it.

Paleo and Alzheimer’s: All About “Type 3 Diabetes”

You might have heard Alzheimer’s disease described as “Type 3 Diabetes,” implying that it’s another “disease of civilization,” a consequence of the modern diet and lifestyle more than anything else. The “Diabetes” label in particular makes it seem like Alzheimer’s is all about the carbs. But it’s actually more complicated than that (isn’t it always?).

Alzheimer’s Disease probably does have something to do with dietary carbs, but it’s much more complicated than “insulin wrecks your brain.” And it also has connections to other parts of the modern diet, especially overload of Omega-6 fats. So here’s a look at Alzheimer’s from a Paleo perspective, focusing on the potential role of diet in long-term prevention and therapy.

This post is not an explanation of how to “cure” Alzheimer’s Disease, or even what causes it, and if you meet anyone trying to tell you either of those things, they’re probably lying. It’s just a look at some possible connections between diet and Alzheimer’s

What Is Alzheimer’s Disease?

Alzheimer’s Disease is a progressive, age-related brain disease that starts off by causing forgetfulness and confusion and progresses to more serious problems like mood, language, and behavioral issues. A few people get it earlier, but it’s primarily found in people in their 60s and up.

Alzheimer’s isn’t just an extension of normal age-related forgetfulness, though. In Alzheimer’s Disease, neurons in the brain actually die – this doesn’t happen in normal aging, even though most people’s brains do shrink a little bit with age.

In most cases of Alzheimer’s, nobody’s really sure what causes it – we can identify hallmark signs of the disease (amyloid-beta plaques and tangled proteins) and certain genes that make people more susceptible, but there’s no one thing that anyone can point to and definitively claim that it’s what “causes Alzheimer’s.”

As populations in most Western countries get older, Alzheimer’s is becoming an increasingly important health concern, especially because it’s connected to some other rapidly-growing “epidemics:” obesity and diabetes. The association with other notorious “lifestyle diseases” implies that Alzheimer ’s Disease might share some of the same dietary and lifestyle roots.

Alzheimer’s Disease as “Type 3 Diabetes?”

The biggest diet-related risk factor that everyone in the Paleo world likes to point out for Alzheimer’s is diabetes. People with diabetes are much more likely to develop Alzheimer’s than the general population, and it’s likely that this is a consequence of the diabetes itself (not just an association). Diabetes is primarily a disease of glucose (carbohydrate) metabolism, and there’s strong evidence that impaired glucose metabolism in the brain plays a role in the development of Alzheimer’s by depriving cells of energy. If your brain cells are dependent on carbs for energy, but your ability to metabolize carbs is compromised, your brain cells aren’t going to do very well. What’s more, some initial research suggests that ketogenic diets (which provide the brain with fat instead of glucose as fuel) may be helpful as a therapy.

This particular problem even has a name: “Type 3 Diabetes” is the insulin resistance in the brain associated with Alzheimer’s Disease. (if you need a brush-up on insulin, glucose metabolism, and other related issues, here’s a quick explanation of what insulin is, and here’s an overview of what “glucose tolerance”/”carbohydrate tolerance” actually means and why it’s important.)

Another piece of evidence supporting the “Type 3 Diabetes” theory is that other known risk factors associated with Alzheimer’s are also directly or indirectly connected to impaired glucose metabolism. Risk factors for Alzheimer’s include…

• Sleep apnea (a sleep disorder where the patient wakes up many times during the night; it reduces the benefits of sleeping and deprives the brain of oxygen). Sleep apnea reduces insulin sensitivity and increases the risk of metabolic disorders like diabetes, so it might contribute to Alzheimer’s by messing up glucose metabolism even more.
• Physical inactivity. Regular movement makes for good glucose tolerance; a sedentary lifestyle is one big step towards the opposite, so it’s not surprising that it’s a major risk factor for both diabetes and Alzheimer’s.
• Depression. Insulin metabolism problems may contribute to depression, so depression may be one sign of a less-than-optimal insulin metabolism.
• Obesity. Obesity and diabetes often go hand in hand – they’re both associated with problems metabolizing carbohydrates.
• Smoking. Smoking impairs insulin sensitivity, and quitting improves it.

In other words, a lot of the risk factors for Alzheimer’s tie into insulin and glucose metabolism one way or another. The connection with diabetes, plus the tentative research showing a benefit for ketogenic diets, leads a lot of people to conclude that carbs “cause Alzheimer’s” and that a ketogenic diet is the only way to prevent it. But as usual, the simplification doesn’t hold up under closer scrutiny.

“Carbs” as a group means nothing unless you separate “carbohydrate overload in the context of an inflammatory and obesogenic diet full of gut irritants” from “carbohydrates from whole foods in the context of an anti-inflammatory diet low in gut irritants.” The first is associated with Alzheimer’s; the second is not. An inflammatory, obesogenic diet that also happens to be high in carbs may contribute to Alzheimer’s (among other problems), and that a lower-carb diet may be helpful as a treatment, but that doesn’t mean that whole-food carbs in an anti-inflammatory context are dangerous.

But wait a minute, where’s all the talk about inflammation coming from?

Diet and Alzheimer’s: The Inflammation Connection

If you want an inflammatory diet high in Omega-6 oils and simple carbs, this is the way to eat.

If you look at all the risk factors above again, you’ll notice another big problem in common: inflammation. All the risk factors for Alzheimer’s Disease are inflammatory, and neurodegenerative diseases, including Alzheimer’s, are marked by inflammation in the brain. Psychiatrist Emily Deans explains that the particular type of inflammation in Alzheimer’s is related to an imbalance of Omega-6 and Omega-3 fats – fat quality as much as carbs might be a factor here.

When you combine an overload of simple carbohydrates with an inflammatory fatty acid profile, what do you get? A typical Western diet high in refined grains and industrial seed oils. It’s not evidence that eating these foods “causes Alzheimer’s” in the same way that streptococcus bacteria cause strep throat, but it’s evidence that a typical Western dietary pattern might be one small factor in the development of Alzheimer’s. And it might point to a diet low in simple carbohydrates with an anti-inflammatory fatty acid profile as a potential way to minimize whatever percentage of Alzheimer’s risk is caused by diet in the first place. Guess what kind of diet is anti-inflammatory and low in simple carbohydrates?

Paleo and Alzheimer’s: Summing it Up

Diet doesn’t “cause” Alzheimer’s Disease. But it does seem that an overall dietary pattern high in both simple carbohydrates and junk fats might contribute to it by depriving the brain of energy and increasing the inflammatory response.

The evidence for this comes partly from research studying the death of neurons and the formation of plaques and tangles in the brain, and partly from epidemiological research connecting inflammatory and insulin-related diseases to an increased likelihood of developing Alzheimer’s later in life.

The evidence that we have suggests that an anti-inflammatory diet (low in total PUFA and especially Omega-6, with adequate amounts of Omega-3) with relatively few refined carbohydrates might be protective against Alzheimer’s insofar as diet can be protective against Alzheimer’s at all (remember that a huge part of it is genetic). Research into ketogenic diets for people who already have cognitive impairment is promising, but it’s always good to be cautious interpreting it and remember that the more complicated the problem, the less likely it is to have one simple solution. P.S. Check out Paleo Restart, our full 30-day program. It comes with the tools to reset your body, lose weight and feel great.

Our cookbook, the Paleo Recipe Book, is also available. It's a cookbook we've created to help you eat delicious Paleo food.

Article reference: http://paleoleap.com/paleo-alzheimers-type-3-diabetes/