Tuesday, April 5, 2011



By Monika Tarkowska-Carter, CPT, LWMC, HLC 2

Every day we are faced with troubling statistics about the health of Americans. We are the fattest nation on Earth, with 65% of us being either obese or overweight. We all know that this very fact increases our susceptibility to so many diseases: heart attacks, strokes, cardiovascular disease, high blood pressure, diabetes and insulin resistance, asthma, high cholesterol, metabolic syndrome, cancer, etc., etc. The list goes on and on.
We take more medications than ever in our history, yet we struggle more, not less, not only with diseases, but also depression and, as recent statistics show us, insomnia, or just plain lack of sleep.
Could this fact somehow contribute to our ever-expending waistlines? Could we become slimmer just by sleeping more?
Recent research shows that the answer is YES. A few of the hormones produced by our body are responsible for predisposing us to weight gain when the body is faced with sleep deprivation.

One of them is leptin – a hormone released by the fat cells that tells your brain you’re full and signals satiety. The other one is ghrelin – a peptide secreted by the stomach that stimulates appetite. When people get 7 hours of sleep or more, on average, the amounts of these hormones in the blood remain at their normal levels. With lack of sleep, however, the levels of leptin go down and the levels of ghrelin increase, causing you to be less satisfied after you eat, perceive that you’re still hungry, as well as eat more since your appetite is stimulated. Translation: weight gain.
Interestingly, in the study done on subjects whose sleep was restricted to 4 hours per night for 6 days, the level of plasma leptin so drastically decreased that it was comparable to restricting calories by 900kcal/day for 3 days. These subjects received the exact same amount of calories and had similar levels of physical activity as when they were fully rested (1), which means that the lowered leptin levels signaled a state of famine to the body, even though there were plenty of calories available. Whenever our bodies perceive famine, they start conserving energy and storing calories instead of expending them. Translation: weight gain.

Studies done at the University of Colorado and at Stanford University in California, that measured the levels of the above hormones in sleep deprived people, showed that not only did cravings for high carbohydrate, high calorie foods increased by 45% in the test subjects , but their body fat percentage was also higher. The level of body fat was inversely correlated to their sleep patterns. The weight was the highest in subjects getting the fewest hours of sleep.
The other hormones that may affect your pant size just as much are insulin and cortisol. With sleep deprivation, your body’s ability to use insulin effectively deteriorates, causing insulin resistance and resultant storage of fat. Translation: weight gain.
The findings from a Dutch study conducted by Esther Donga, director of Leiden Medical Center in the Netherlands and published in the Journal of Clinical Endocrinology & Metabolism (JCEM), showed that partial sleep restriction during a single night reduced some types of insulin sensitivity by 19 to 25 percent. (2)
"Our data indicate that insulin sensitivity is not fixed in healthy (people), but depends on the duration of sleep in the preceding night," the author wrote in the study.
"In fact it is tempting to speculate that the negative effects of multiple nights of shortened sleep on glucose tolerance can be reproduced, at least in part, by just one sleepless night."
In a study conducted by U.S. scientists published in 2009, people who slept less than six hours a night were 4.5 times more likely to develop abnormal blood sugar readings in six years compared with those who slept longer. In fact, studies on glucose levels in sleep deprived people show that “….less than 1 week of sleep restriction can result in a prediabetic state in young, healthy subjects”. (3) Translation: weight gain.
Hormone cortisol, or stress hormone, as it is commonly known, might have something to do with our expending waistlines as well. Cortisol generally has the tendency to make the body store fat, especially in the abdomen area.

Recent studies looked at the impact of chronic partial sleep deprivation on hormones, metabolism and immune function. The first documented effect of partial sleep loss was an increase in the early evening levels of cortisol. (4, 5) This is likely the direct cause of the development of insulin resistance, a huge factor in both diabetes and obesity. (6) Translation: weight gain.
On the other hand, thyroid-stimulating hormone, or TSH, was hugely decreased during the night in sleep deprived subjects, with the overall mean levels reduced by more than 30%. The result would be a drastically decreased metabolic rate and a much smaller amount of calories burnt. Translation: weight gain.
The secretion of Growth Hormone, or GH, which has anti-insulin like effects, was also altered and might therefore adversely impact glucose tolerance. Most likely translation: weight gain.
It turns out that lack of sleep has much more profound influence on metabolic regulation than previously thought. So make sure you get at least 8 hours of good quality sleep each night and you might find that your struggle with weight is going to get much easier. If only we could just wake up 5 pounds lighter……oh well, at least we can dream about it.

1. Spiegel K, Leproult R, L'Hermite-Baleriaux M, et al. Leptin levels are dependent on sleep duration: relationships with sympatho-vagal balance, carbohydrate regulation, cortisol and TSH. J Clin Endocrinol Metab. 2004;89:5762-5771. Abstract
2. Esther Donga, Marieke van Dijk, J. Gert van Dijk, Nienke R. Biermasz, Gert-Jan Lammers, Klaas W. van Kralingen, Eleonara P. M. Corssmit and Johannes A. Romijn. A Single Night of Partial Sleep Deprivation Induces Insulin Resistance in Multiple Metabolic Pathways in Healthy Subjects. Departments of Endocrinology and Metabolic Diseases (E.D., M.v.D., N.R.B., E.P.M.C., J.A.R.), Neurology (J.G.v.D., G.-J.L.), and Pulmonology (K.W.v.K.), Leiden University Medical Center, 2300 RC Leiden, The Netherlands The Journal of Clinical Endocrinology & Metabolism, doi:10.1210/jc.2009-2430 Vol. 95, No. 6 2963-2968
3. Prigeon RL, Kahn SE, Porte D Jr. Changes in insulin sensitivity, glucose effectiveness, and B-cell function in regularly exercising subjects. Metabolism. 1995;44:1259-1263. Abstract
4.Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999;354:1435-1439. Abstract
5. Leproult R, Copinschi G, Buxton O, et al. Sleep loss results in an elevation of cortisol levels the next evening, Sleep. 1997;20:865-870.
6. Eve Van Cauter, PhD; Kristen Knutson, PhD;  Rachel Leproult, PhD; Karine Spiegel, PhD. The Impact of Sleep Deprivation on Hormones and Metabolism.. Medscape Neurology and Neurosurgery > Insomnia and Sleep Health Expert Column

1.     Spiegel K, Leproult R, Van Cauter E.

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