Diabetes
Guest post: Blueberry season
14/Oct/12 12:27 PM
Guest post by Jacob Schor, ND, FABNO
The recent publication of Riso et al’s results in the June issue of the European Journal of Nutrition has left me ruminating on the impact geography plays into our choice of “medicinal foods.”
This study measured the impact of blueberries on a series of biomarkers of oxidative stress. It was a textbook perfect randomized placebo controlled trial with crossover. Eighteen middleaged males (mean age 48 years) drank a smoothie made from freeze-dried wild blueberry powder twice a day for 6 weeks. The drink contained 375 mg of blueberry anthocyanins, equal to about a cup of blueberries. While a long list of biomarkers were evaluated in the participants blood, most did not change significantly. There were two significant changes. Drinking wild blueberry smoothies significantly reduced the levels of endogenously oxidized DNA bases (from 12.5 to 9.6 p ≤ 0.01) and the levels of H(2)O(2)-induced DNA damage (from 45.8 to 37.2 p ≤ 0.01). No effect was found after the placebo drink.
This is interesting to some people. It adds additional weight to the evidence that blueberries are exceptionally healthy foods to eat. We knew this already.
What I’m finding interesting is where this research was done. The lead author, Patrizia Riso and colleagues are from the Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, in Milan, Italy. [1]
Pardon me if I sound politically incorrect, but what are Italians doing studying wild blueberries?
Blueberries are native to North America. Italy has a grand total of only 680 acres of blueberries planted as of 2010.
So what’s going on? It appears that blueberries are suddenly a desirable commodity worldwide. From 2005 to 2010, blueberry the acreage planted in blueberries has increased by 83%. Acreage in North America has increased by 53% and in South America has more than doubled. The western hemisphere, North and South America account for 81% of blueberry acreage. During this period North American acreage has increased by an estimated +53% and South American acreage has more than doubled. As of 2010, North and South America account for 86% of the world’s blueberry acreage producing 491 million and 153 million pounds respectively. The entire Mediterranean and African regions produce a total of only five million pounds. [2]
Perhaps this explains why Riso et al gave their study participants blueberry powder. Fresh blueberries may have been too hard to find. Certainly it would be hard to find real wild blueberries of the sort one collects in mountain meadows in direct competition with hungry bears.
Wondering about these Italian blueberries prompts me to look at the other randomized clinical trials using blueberries.
There is the Wilms’ study published back in August 2007. In that study, 168 volunteers drank a daily glass of blueberry/apple juice for a month. The researchers found that plasma quercetin, ascorbic acid and trolox equivalent antioxidant capacity (TEAC) were all significantly increased. The researchers also reported a 20% protection (P < 0.01) against ex vivo hydrogen peroxide-provoked oxidative DNA damage.
Where was this research done? Maastricht University, The Netherlands. [3]
In 2010 there were just 1,180 acres of blueberries growing in the Netherlands.
An October 2010 paper written by Stull et al and published in Nutrition Journal reported that chemicals in blueberries improve insulin sensitivity in obese, insulin-resistant men and women. In this double-blinded randomized controlled trial, fifteen obese volunteers drank smoothies twice a day, each of which contained 22.5 grams of blueberry “bioactives,” while a control group consumed similar smoothies but without the blueberries. Insulin sensitivity improved more in the blueberry group than in the placebo group. The daily dose of “bioactives” consumed by these study participants contained 668 mg of anthocyanins, and was equivalent to approximately ~2 cups of fresh whole blueberries. These researchers were from Baton Rouge, Louisiana. [4]
The entire state of Louisiana has 466 acres of land planted with commercial blueberries. [5]
An April 2010 study done by researchers from the University of Cincinnati reported that nine older adults who drank a daily serving of wild blueberry juice had significant improvements in cognitive function including paired associate learning and word list recall. They also tended toward a reduction in depressive symptoms. [6] Ohio grows even fewer blueberries than Louisiana, only 378 acres. [7]
A December 2011 published study reported that regular consumption of a blueberry drink improved intestinal flora. After six weeks Bifidobacterium spp. significantly increased. [8] This study was also conducted by Italians. Remember just 680 acres.
A December 2011 paper was written McAnulty et al from Appalachian State University.
This is the research group that specializes in measuring the oxidative impact of strenuous exercise. We’ve written about them in the past. They did the quercetin and bicycle racing studies. In this study they examined the impact of eating 250 gram of blueberries per day for 6 week and then eating a larger dose, 375 grams, an hour before a long hard run (2.5 hours at 72% maximal oxygen consumption). Twenty-five well-trained athletes took part in the study. Compared to a control group who went through the run, the blueberry group had increased natural killer NK counts. Even a single dose of blueberries eaten just before the run, reduces oxidative stress and increases anti-inflammatory cytokines. [9]
North Carolina, finally a state that produces blueberries. They produce almost 12% of the US annual blueberry crop and average about 6,000 acres planted in blueberries each year. [10] Notice that this study used real blueberries.
Given the number and variety of benefits seen in these studies, not to mention the numerous studies done in animals, there seems to be little doubt that blueberries are good for us.
What I find confusing is why the research on blueberries isn’t coming from the state universities in regions known for their blueberries, in particular Maine, Michigan, New Jersey?
This year’s wild blueberry crop in Maine is predicted to be the largest in history. Maine has over 60,000 acres of wild blueberries that are managed for picking. [11,12]
I can’t help but think that scientists fall prey to the same sort of attraction to novelty as the rest of us. Americans now purchase anything that claims to contain Acai berry. Marketers find a willing audience when they sell exotic fruit juices from Hawaii or Thailand, juices that taste horrible but are still consumed for their health benefits. Is it any wonder that the Italians and Dutch are fascinated with blueberries?
References:
- Riso P, Klimis-Zacas D, Del Bo' C, Martini D, Campolo J, Vendrame S, Møller P, Loft S, De Maria R, Porrini M. Effect of a wild blueberry (Vaccinium angustifolium) drink intervention on markers of oxidative stress, inflammation and endothelial function in humans with cardiovascular risk factors. Eur J Nutr. 2012 Jun 26.
- http://www.growingproduce.com/article/26272/2/trends-in-world-blueberry-production
- Wilms LC, Boots AW, de Boer VC, Maas LM, Pachen DM, Gottschalk RW, et al. Impact of multiple genetic polymorphisms on effects of a 4-week blueberry juice intervention on ex vivo induced lymphocytic DNA damage in human volunteers. Carcinogenesis. 2007 Aug;28(8):1800-6.
- Stull AJ, Cash KC, Johnson WD, Champagne CM, Cefalu WT. Bioactives in blueberries improve insulin sensitivity in obese, insulin-resistant men and women. J Nutr. 2010 Oct;140(10):1764-8.
- http://www.lsuagcenter.com/agsummary/narrative
- Krikorian R, Shidler MD, Nash TA, Kalt W, Vinqvist-Tymchuk MR, Shukitt-Hale B, Joseph JA. Blueberry supplementation improves memory in older adults. J Agric Food Chem. 2010 Apr 14;58(7):3996-4000.
- http://www.agriculture.purdue.edu/aganswers/story.asp?storyID=6738
- Vendrame S, Guglielmetti S, Riso P, Arioli S, Klimis-Zacas D, Porrini M. Six-week consumption of a wild blueberry powder drink increases bifidobacteria in the human gut. J Agric Food Chem. 2011 Dec 28;59(24):12815-20.
- McAnulty LS, Nieman DC, Dumke CL, Shooter LA, Henson DA, Utter AC, et al. Effect of blueberry ingestion on natural killer cell counts, oxidative stress, and inflammation prior to and after 2.5 h of running. Appl Physiol Nutr Metab. 2011 Dec;36(6):976-84.
- North Carolina, finally a state that produces blueberries. They produce almost 12 % of the US annual blueberry crop.
- http://bangordailynews.com/2012/07/29/business/maine-blueberries-producing-biggest-crop-in-a-decade/
- http://umaine.edu/blueberries/
Comments
Diabetes talk May 23rd
18/May/12 09:56 PM
by Kate Whimster, BCom, MIFHI, ND
I will be giving at free talk about Type II Diabetes on Wednesday, May 23rd, 7pm at the Main Street Library (137 Main Street, Toronto). Call the library at 416-393-7700 to RSVP!
Learn about the physiology of blood sugar control and how type II diabetes can be effectively prevented and treated via safe, natural interventions.
See my Appearances and Events page for more upcoming dates and topics!
I will be giving at free talk about Type II Diabetes on Wednesday, May 23rd, 7pm at the Main Street Library (137 Main Street, Toronto). Call the library at 416-393-7700 to RSVP!
Learn about the physiology of blood sugar control and how type II diabetes can be effectively prevented and treated via safe, natural interventions.
See my Appearances and Events page for more upcoming dates and topics!
Diabetes talk May 16th
09/May/12 10:20 AM
by Kate Whimster, BCom, MIFHI, ND
I will be giving a free talk about Type II Diabetes on Wednesday, May 16th, 7pm at the Deer Park Library (40 St. Clair Avenue East, Toronto). Call the library at 416-393-7657 to RSVP!
Learn about the physiology of blood sugar control and how type II diabetes can be effectively prevented and treated via safe, natural interventions.
See my Appearances and Events page for more upcoming dates and topics!
I will be giving a free talk about Type II Diabetes on Wednesday, May 16th, 7pm at the Deer Park Library (40 St. Clair Avenue East, Toronto). Call the library at 416-393-7657 to RSVP!
Learn about the physiology of blood sugar control and how type II diabetes can be effectively prevented and treated via safe, natural interventions.
See my Appearances and Events page for more upcoming dates and topics!
Guest post: The scoop on fish oils
25/Nov/11 05:27 PM
Guest post originally published by Negin Misaghi, ND
I’m not much into miracles especially where medicine is concerned. Fish oils however, are without question today’s miracle medicine! I should clarify however that fish oil is a miracle in the sense that it’s a very potent healer, and not a miracle as far as the definition of this word is concerned - with regards to it being supernatural or incomprehensible. Far from it! In fact, the mechanism of action of fish oils with regards to its therapeutic effects are very well understood.
Everything in our lifestyle from our standard diet to our hectic stress-filled day-to-day living, to our sedentary city life of drive-through’s and desk jobs, and machines of all functionalities has made us ‘inflammatory’ – in every sense of the word!
From a Traditional Chinese Medicine perspective, our inflammatory and stress-filled lifestyle causes damage to the liver. Once the liver has reached its capacity, damages begin to affect the heart and kidneys also. Chinese Medicine among many traditional medical beliefs (like Ayurveda and others) links each organ system to an emotion. The liver when pathological causes feelings of anger - hence, inflammation in every sense of the word! When damages reach the heart, depression and anxiety set in, and once the kidneys begin to take the grunt of the insult and are damaged, fears and insecurities begin to surface (just to show how entwined our body systems are where an imbalance of one system puts pressure on others and if chronic, can upset the harmony of the whole body).
This is where fish oils can have a great impact on the health of an individual both physically as well as mentally and emotionally. Fish oils have demonstrated strong anti-inflammatory properties for conditions that are inflammatory in nature (arthritis, heart disease, metabolic syndrome and insulin insensitivity (diabetes)). As well, fish oils have been found to be effective for the treatment of depression (recent research has linked depression to chronic inflammation).
Although fish oils benefit almost every health condition of today as most result from chronic inflammation, it should also be noted that if there’s still gas feeding the fire of inflammation (i.e. the root cause of inflammation has not been removed), fish oils would only be a band-aid solution. To learn more about how inflammation can be controlled at its root, seek the advice of a licensed naturopathic doctor. In the meantime, consider supplementation with fish oils to keep inflammation in check!
I should also mention that the EPA component of fish oil is responsible for its anti-inflammatory properties and NO vegetarian source of Omega 3’s contains EPA.
To be discussed in a later post: Why animal sources of omega 3′s are superior to vegetarian sources, why dietary sources of fish oils are not sufficient for some, and best(safe) fish to consume for their omega 3 content!
Sleep and metabolic syndrome
24/Nov/09 10:56 AM
by Kate Whimster, BCom, MIFHI, ND
I wrote a research paper looking the relationship between sleep duration and metabolic syndrome and this blog is a summary of what I learned. References are listed at the end and can be found on PubMed.
Metabolic syndrome is a group of metabolic risk factors used to identify individuals at risk for cardiovascular disease (1). A correlation between sleep duration and the development of metabolic syndrome has been observed.
The National Cholesterol Education Program (NCEP) Adult Treatment Panel III diagnosis of metabolic syndrome requires the presence of three or more of the following features (1):
1. Waist circumference:
- Men: Greater than or equal to 102cm (40in)
- Women: Greater than or equal to 88cm (35in)
2. Triglycerides: Greater than or equal to 1.7mmol/L (150 mg/dL)
3. HDL cholesterol:
- Men: Less than 1.0mmol/L (40mg/dL)
- Women: Less than 1.3mmol/L (50mg/dL)
4. Blood pressure: Greater than or equal to 130/85 mmHg or medicated for hypertension
5. Fasting blood glucose: Greater than or equal to 5.6mmol/L (100mg/dL) or medicated for hyperglycemia
First-line treatment focuses on lifestyle factors such as dietary modification and increased physical activity (1). However, given that “‘normal’ average sleep duration has decreased from about 9 h per night in 1910 to about 7.5 h currently, (2)” and mounting evidence that sleep deprivation causes physiological changes that lead to metabolic syndrome, sleep deprivation is another important lifestyle factor to consider.
Short sleep duration (less than 6 hours per night) is associated with the highest risk for metabolic syndrome, but long sleep duration (more than 8 or 9 hours per night) is also associated with increased risk. The lowest risk was seen in subjects sleeping 7-8 hours per night (3,4).
With regards to abdominal obesity, “very short and short sleepers were at least 1.6 times more likely to meet criteria for abdominal obesity … compared with individuals who slept 7 to 8 hours per night (4).”
There is also a correlation between insulin resistance and sleep duration, both short and long: “with the reference group, the odds of meeting the glucose criterion were at least 1.7 times greater in the very short (< 6 hours) and long (> 8 hours) sleeper groups (4).” It is also likely that insulin resistance due to altered metabolism resulting from inadequate sleep develops gradually over years. One study restricted sleep in healthy young men to four hours per night for six nights and found that sleep debt led to impaired carbohydrate tolerance. Decreased morning insulin sensitivity was observed after 6 days of sleep restriction compared to when subjects were fully rested (6). “These results suggest that insulin sensitivity was lower on the 6th than on the 5th day of sleep restriction and thus that insulin resistance may develop progressively with increasing exposure to partial sleep loss (5).”
The Sleep Heart Health Study found that sleep duration was associated with risk of hypertension, with those sleeping less than 6 and 6-7 hours and those sleeping 8-9 and 9 or more hours demonstrating increased risk (6). A longitudinal analyses of the first National Health and Nutrition Examination Survey demonstrated that sleep durations of “< or =5 hours per night were associated with a significantly increased risk of hypertension … in subjects between the ages of 32 and 59 years (7).”
The studies discussed above have also found a relationship between increased sleep and metabolic syndrome. When examined more closely in one study, relationships between long sleep duration and metabolic syndrome and elevated glucose “were no longer significant with adjustment for use of antihypertensive medication, which has been shown to impact fasting blood glucose levels (4).” There is also a relationship between long sleep duration and sleep apnea, suggesting that “long sleep duration is a proxy for sleep disordered breathing and that sleep apnea drives the relationship between long sleep duration and health outcomes (4).”
Sleep quality is also an important factor to consider. An observational, cross-sectional study demonstrated that “poor global sleep-quality scores on the Pittsburgh Sleep Quality Index were related significantly to the presence of the metabolic syndrome (8).”
Studies relating sleep duration to metabolic changes are often confounded by pre-existing conditions (such as diabetes or hypertension), lifestyle habits (such as smoking, diet, alcohol intake, and caffeine intake), and other factors affecting sleep (such as sleep apnea). It is therefore important that studies of sleep duration take these factors into account and control for them as much as possible in order to establish a clear relationship between sleep and health outcomes. One researcher has challenged the above conclusions by offering three criticisms. First, “few obese adults/children are short sleepers, and few short sleeping adults/children are obese or suffer obesity-related disorders (9).” Second, the clinical risk only emerges from very short or long sleep duration and develops over many years, so while acute sleep restriction does lead to leads to glucose intolerance and metabolic syndrome “this is too little sleep and cannot be sustained beyond a few days (9).” Finally, he offers an alternative explanation for the relationship between sleep and metabolism: “habitually insufficient sleep could contribute towards obesity, metabolic syndrome, etc., via sleepiness-related inactivity and excess energy intake (9).”
It seems obvious that sleep is an important factor in health, but it is often overlooked by both conventional and naturopathic practitioners. Based on the studies discussed, the optimal sleep duration is between 7-8 hours per night. Many patients fail to prioritize sleep or have trouble falling asleep easily, both issues that can be greatly aided by naturopathic interventions. Sleep quality is also an important consideration and naturopathic doctors are also well equipped to make recommendations in this area.
1. MD Consult. Metabolic Syndrome. Accessed 18 Nov 2008. Available at: http://www.mdconsult.com.
2. Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999 Oct 23;354(9188):1435-9.
3. Choi KM, Lee JS, Park HS, Baik SH, Choi DS, Kim SM. Relationship between sleep duration and the metabolic syndrome: Korean National Health and Nutrition Survey 2001. Int J Obes (Lond). 2008 Jul;32(7):1091-7. Epub 2008 May 13.
4. Hall MH, Muldoon MF, Jennings JR, Buysse DJ, Flory JD, Manuck SB. Self-reported sleep duration is associated with the metabolic syndrome in midlife adults. Sleep. 2008 May 1;31(5):635-43.
5. Knutson KL, Spiegel K, Penev P, Van Cauter E. The metabolic consequences of sleep deprivation. Sleep Med Rev. 2007 Jun;11(3):163-78. Epub 2007 Apr 17. Review.
6. Gottlieb DJ, Redline S, Nieto FJ, Baldwin CM, Newman AB, Resnick HE, Punjabi NM. Association of usual sleep duration with hypertension: the Sleep Heart Health Study. Sleep. 2006 Aug 1;29(8):1009-14.
7. Gangwisch JE, Heymsfield SB, Boden-Albala B, Buijs RM, Kreier F, Pickering TG, Rundle AG, Zammit GK, Malaspina D. Short sleep duration as a risk factor for hypertension: analyses of the first National Health and Nutrition Examination Survey. Hypertension. 2006 May;47(5):833-9. Epub 2006 Apr 3.
8. Jennings JR, Muldoon MF, Hall M, Buysse DJ, Manuck SB. Self-reported sleep quality is associated with the metabolic syndrome. Sleep. 2007 Feb 1;30(2):219-23.
9. Horne JA. Short sleep is a questionable risk factor for obesity and related disorders: statistical versus clinical significance. Biol Psychol 2008;77:266-76.
I wrote a research paper looking the relationship between sleep duration and metabolic syndrome and this blog is a summary of what I learned. References are listed at the end and can be found on PubMed.
Metabolic syndrome is a group of metabolic risk factors used to identify individuals at risk for cardiovascular disease (1). A correlation between sleep duration and the development of metabolic syndrome has been observed.
The National Cholesterol Education Program (NCEP) Adult Treatment Panel III diagnosis of metabolic syndrome requires the presence of three or more of the following features (1):
1. Waist circumference:
- Men: Greater than or equal to 102cm (40in)
- Women: Greater than or equal to 88cm (35in)
2. Triglycerides: Greater than or equal to 1.7mmol/L (150 mg/dL)
3. HDL cholesterol:
- Men: Less than 1.0mmol/L (40mg/dL)
- Women: Less than 1.3mmol/L (50mg/dL)
4. Blood pressure: Greater than or equal to 130/85 mmHg or medicated for hypertension
5. Fasting blood glucose: Greater than or equal to 5.6mmol/L (100mg/dL) or medicated for hyperglycemia
First-line treatment focuses on lifestyle factors such as dietary modification and increased physical activity (1). However, given that “‘normal’ average sleep duration has decreased from about 9 h per night in 1910 to about 7.5 h currently, (2)” and mounting evidence that sleep deprivation causes physiological changes that lead to metabolic syndrome, sleep deprivation is another important lifestyle factor to consider.
Short sleep duration (less than 6 hours per night) is associated with the highest risk for metabolic syndrome, but long sleep duration (more than 8 or 9 hours per night) is also associated with increased risk. The lowest risk was seen in subjects sleeping 7-8 hours per night (3,4).
With regards to abdominal obesity, “very short and short sleepers were at least 1.6 times more likely to meet criteria for abdominal obesity … compared with individuals who slept 7 to 8 hours per night (4).”
There is also a correlation between insulin resistance and sleep duration, both short and long: “with the reference group, the odds of meeting the glucose criterion were at least 1.7 times greater in the very short (< 6 hours) and long (> 8 hours) sleeper groups (4).” It is also likely that insulin resistance due to altered metabolism resulting from inadequate sleep develops gradually over years. One study restricted sleep in healthy young men to four hours per night for six nights and found that sleep debt led to impaired carbohydrate tolerance. Decreased morning insulin sensitivity was observed after 6 days of sleep restriction compared to when subjects were fully rested (6). “These results suggest that insulin sensitivity was lower on the 6th than on the 5th day of sleep restriction and thus that insulin resistance may develop progressively with increasing exposure to partial sleep loss (5).”
The Sleep Heart Health Study found that sleep duration was associated with risk of hypertension, with those sleeping less than 6 and 6-7 hours and those sleeping 8-9 and 9 or more hours demonstrating increased risk (6). A longitudinal analyses of the first National Health and Nutrition Examination Survey demonstrated that sleep durations of “< or =5 hours per night were associated with a significantly increased risk of hypertension … in subjects between the ages of 32 and 59 years (7).”
The studies discussed above have also found a relationship between increased sleep and metabolic syndrome. When examined more closely in one study, relationships between long sleep duration and metabolic syndrome and elevated glucose “were no longer significant with adjustment for use of antihypertensive medication, which has been shown to impact fasting blood glucose levels (4).” There is also a relationship between long sleep duration and sleep apnea, suggesting that “long sleep duration is a proxy for sleep disordered breathing and that sleep apnea drives the relationship between long sleep duration and health outcomes (4).”
Sleep quality is also an important factor to consider. An observational, cross-sectional study demonstrated that “poor global sleep-quality scores on the Pittsburgh Sleep Quality Index were related significantly to the presence of the metabolic syndrome (8).”
Studies relating sleep duration to metabolic changes are often confounded by pre-existing conditions (such as diabetes or hypertension), lifestyle habits (such as smoking, diet, alcohol intake, and caffeine intake), and other factors affecting sleep (such as sleep apnea). It is therefore important that studies of sleep duration take these factors into account and control for them as much as possible in order to establish a clear relationship between sleep and health outcomes. One researcher has challenged the above conclusions by offering three criticisms. First, “few obese adults/children are short sleepers, and few short sleeping adults/children are obese or suffer obesity-related disorders (9).” Second, the clinical risk only emerges from very short or long sleep duration and develops over many years, so while acute sleep restriction does lead to leads to glucose intolerance and metabolic syndrome “this is too little sleep and cannot be sustained beyond a few days (9).” Finally, he offers an alternative explanation for the relationship between sleep and metabolism: “habitually insufficient sleep could contribute towards obesity, metabolic syndrome, etc., via sleepiness-related inactivity and excess energy intake (9).”
It seems obvious that sleep is an important factor in health, but it is often overlooked by both conventional and naturopathic practitioners. Based on the studies discussed, the optimal sleep duration is between 7-8 hours per night. Many patients fail to prioritize sleep or have trouble falling asleep easily, both issues that can be greatly aided by naturopathic interventions. Sleep quality is also an important consideration and naturopathic doctors are also well equipped to make recommendations in this area.
1. MD Consult. Metabolic Syndrome. Accessed 18 Nov 2008. Available at: http://www.mdconsult.com.
2. Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999 Oct 23;354(9188):1435-9.
3. Choi KM, Lee JS, Park HS, Baik SH, Choi DS, Kim SM. Relationship between sleep duration and the metabolic syndrome: Korean National Health and Nutrition Survey 2001. Int J Obes (Lond). 2008 Jul;32(7):1091-7. Epub 2008 May 13.
4. Hall MH, Muldoon MF, Jennings JR, Buysse DJ, Flory JD, Manuck SB. Self-reported sleep duration is associated with the metabolic syndrome in midlife adults. Sleep. 2008 May 1;31(5):635-43.
5. Knutson KL, Spiegel K, Penev P, Van Cauter E. The metabolic consequences of sleep deprivation. Sleep Med Rev. 2007 Jun;11(3):163-78. Epub 2007 Apr 17. Review.
6. Gottlieb DJ, Redline S, Nieto FJ, Baldwin CM, Newman AB, Resnick HE, Punjabi NM. Association of usual sleep duration with hypertension: the Sleep Heart Health Study. Sleep. 2006 Aug 1;29(8):1009-14.
7. Gangwisch JE, Heymsfield SB, Boden-Albala B, Buijs RM, Kreier F, Pickering TG, Rundle AG, Zammit GK, Malaspina D. Short sleep duration as a risk factor for hypertension: analyses of the first National Health and Nutrition Examination Survey. Hypertension. 2006 May;47(5):833-9. Epub 2006 Apr 3.
8. Jennings JR, Muldoon MF, Hall M, Buysse DJ, Manuck SB. Self-reported sleep quality is associated with the metabolic syndrome. Sleep. 2007 Feb 1;30(2):219-23.
9. Horne JA. Short sleep is a questionable risk factor for obesity and related disorders: statistical versus clinical significance. Biol Psychol 2008;77:266-76.
