Linking Sleep Loss and Obesity
Results from a 2003-2004 National Health and Nutrition Examination Survey indicate that an estimated 66 percent of U.S. adults are either overweight or obese. The same survey indicates that an estimated 17 percent of children and adolescents ages 2-19 years are overweight.
Since the mid-seventies, the prevalence of overweight and obesity has increased significantly for both adults and children:
• Among adults aged 20–74 years the prevalence of obesity increased from 15.0% (in the 1976–1980 survey) to 32.9% (in the 2003–2004 survey).
• For children aged 2–5 years, prevalence increased from 5.0% to 13.9%; for those aged 6–11 years, prevalence increased from 6.5% to 18.8%; and for those aged 12–19 years, prevalence increased from 5.0% to 17.4%.
According to Circadian Technologies, Inc. 71% of men, and 53% of women extended hours workers (shift workers) are overweight.[1]
Overweight and obesity result from an energy imbalance; eating too many calories and not getting enough physical activity. Body weight is the result of genes, metabolism, behavior, environment, culture, and socioeconomic status. Behavior and environment play a large role causing people to be overweight and obese. These are the greatest areas for prevention and treatment actions. [2]
Only 27.5% of shift workers report having good nutritional practices. And, 78% of shift workers age 18-24 report not being aware of, or not having, good nutritional habits. In addition, 77% of shift workers report that they do not exercise regularly.[3]
And, shift workers sleep an average 6.5 hours on workdays; nightshift-only workers sleep even less. [4] Numerous studies have shown that people who sleep less weigh more:
• A study presented to the North American Association for the Study of Obesity found that people who only slept two to four hours a night were 73% more likely to be obese than normal sleepers.
• The Wisconsin Sleep Cohort Study looked at the sleep patterns of 1,024 participants starting in 1989; they found that people sleeping less than 8 hours (74.4% of the sample) had increased BMI (body mass index) proportional to the decreased sleep. Note: although BMI correlates with the amount of body fat, it does not directly measure body fat. Some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat.
• In a French study of 1,031 five year old children, those sleeping less than 11 hours a night were significantly more obese.
• In a Japanese study of 8,274 children, aged six to seven years, the odds of obesity were about three times greater for sleep of less than eight hours a night, compared with sleep of 10 hours.
• A Spanish study of 1,772 adolescents (15 years or older) reported an association between short sleep duration and obesity.
• Using sleep data of 1.1 million adults from the American Cancer Society, a relationship between short sleep duration and obesity was observed; an association between sleep duration and mortality.
• In a study of 496 Swiss adults over 13 years, there was an increase in BMI from 21.8 kg/m2 (age 27 years) to 23.3 kg/m2 (age 40 years), with a concurrent decrease in sleep duration from 7.1 to 6.9 hours a night in men, and from 7.7 to 7.3 hours in women; however, the association between short sleep duration and obesity decreased with age.
• Research by Warwick Medical School at the University of Warwick has found that sleep deprivation is associated with an almost a two-fold increased risk of being obese for both children and adults; the research reviewed current evidence in over 28,000 children and 15,000 adults.
Looking for reasons why shorter sleep is correlated to increased risk of obesity, researchers have linked shorter sleep duration with imbalances in two hormones, leptin and ghrelin. Leptin is produced by fat cells and tells the brain when to stop eating. Ghrelin, which is produced by the stomach, triggers hunger. Leptin levels decline and ghrelin levels rise in people who are not getting enough sleep. So, too low or too high leptin levels will lead to being hungry and never feeling full. This process is complicated by two other hormones: insulin, which also regulates weight gain and increases appetite, and serotonin, which must be released if a feeling of fullness is to be achieved.
According to the Center for Disease Control, people who are overweight, particularly obese individuals are at increased risk for many diseases and health conditions, including the following:
• Hypertension (high blood pressure)
• Osteoarthritis (a degeneration of cartilage and its underlying bone within a joint)
• Dyslipidemia (for example, high total cholesterol or high levels of triglycerides)
• Type 2 diabetes
• Coronary heart disease
• Stroke
• Gallbladder disease
• Sleep apnea and respiratory problems
• Some cancers (endometrial, breast, and colon)
Obese workers can cost employers more in health care expenses. A study conducted by Duke University researchers, published in the April 23, 2007 issue of Archives of Internal Medicine, looked at data from a survey of 11,728 people employed by NC-based Duke who had at least one health risk appraisal between 1997 and 2004. Among participants in the study, overweight workers with a body mass index of more than 40 had 13 times more lost workdays due to work-related injuries than their more-fit co-workers. Medical claim costs were seven times higher for obese workers.
Shift workers have up to a 50% increase of cardiovascular disease. Nearly 12% of shift workers have obstructive sleep apnea, compared to 2%-4% of the regular population. Shift workers have a higher prevalence of diabetes than day-time workers. [5] More studies on the effect of sleep loss on food intake, exercise and obesity are clearly needed.
[1] Circadian Technologies, Inc. Health in Extended Hours Operations: Understanding the Challenges, Implementing the Solutions, copyright 2003
[2] Adapted from U.S. Surgeon General’s Call to Action to Prevent and Decrease Overweight and Obesity, 2001
[3] Circadian Technologies, Inc. Health in Extended Hours Operations: Understanding the Challenges, Implementing the Solutions, copyright 2003
[4] Circadian Technologies, Inc. Health in Extended Hours Operations: Understanding the Challenges, Implementing the Solutions, copyright 2003
[5] Circadian Technologies, Inc. Health in Extended Hours Operations: Understanding the Challenges, Implementing the Solutions, copyright 2003
©2008workingnights
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Tags: circadian rhythms, diabetes, health costs, napping, obesity, sleep
