Sleep Apnea Increases in the US Population

To anyone involved in bariatric care, screening for sleep apnea should be an essential part of clinical assessment. Thus, not surprisingly, a substantial proportion of bariatric patients are diagnosed with this condition and receive (often life-changing) therapy. But how common is this condition in the overall population? This question is addressed in a paper by Peppard and colleagues published in the American Journal of Epidemiology. Based on data in bout 1,500 participants from the Wisconsin Sleep Cohort Study, an ongoing community-based study established in 1988 with participants randomly selected from an employed population of Wisconsin adults, prevalence of sleep-disordered breathing in the United States for the periods of 1988-1994 and 2007-2010 was estimated using NHANES data for age, sex, and body mass index. Based on these estimates, the current prevalence of moderate to severe sleep-disordered breathing (apnea-hypopnea index, measured as events/hour, ≥15) in the US are 10% among 30-49-year-old men; 17% among 50-70-year-old men; 3% among 30-49-year-old women; and 9% among 50-70 year-old women. Not only do these estimated prevalence rates represent a substantial increase over the last 2 decades but, as expected even higher rates of sleep apnea are seen in the more obese section of the population. Thus, sleep apnea is certainly a condition that will require a lot of attention both in terms of diagnostics and management. AMS Edmonton, Alberta Peppard PE, Young T, Barnet JH, Palta M, Hagen EW, & Hla KM (2013). Increased Prevalence of Sleep-Disordered Breathing in Adults. American journal of epidemiology PMID: 23589584     .

Even a Modest Lack of Sleep Can Adversely Affect Metabolism

Kevin is a healthy 24 year old student with a BMI of 25, who usually sleeps almost 8 hrs (7:45 to be precise). He is usually fast asleep within 20 mins of lying down and has good quality sleep. Having always had some interest in research, Kevin (together with 18 other healthy young male students) volunteers to take part in a study on sleep restriction at the University of Surrey, UK, conducted by Denise Robertson and colleagues, the results of which are now published in METABOLISM. Before beginning the study, the researchers measured Kevin’s body composition (he had 16% body fat), his blood pressure (normal), glucose and insulin levels (normal), adiponectin, leptin and even performed a euglycemic insulin clamp to measure his insulin sensitivity. As a result of randomization, Kevin ended up in the sleep restriction group and now had to set his daily alarm clock for 1.5 hours before his normal waking time for the next three weeks. He was also told not to nap during the day. Close activity monitoring ensured that he did not cheat on the protocol. During the first two weeks of sleeping less, Kevin’s body weight actually decreased by about 4 lbs, only to increase slightly above baseline at the end of the study. Similarly, he became more insulin resistant after one week of sleep deprivation, but this returned to normal at the end of three weeks . Although not much happened to Kevin’s leptin levels during the first two weeks, they fell sharply in week three and were significantly lower than at baseline by the end of the study. (Not much happened with Kevin’s adiponectin levels.) While Kevin and his colleagues in the sleep deprivation group were experiencing these hormonal changes, not much was happening to the students randomizes to the habitual sleep control group. As the authors note, the metabolic response to mild sleep deprivation appears to be variable over time with some early changes that may not be sustained over time. However, they also note that effects of lowered levels of leptin (seen in the third weed) on hypothalamic centres regulating appetite, could potentially lead to increased food intake and weight gain. This, would need to be looked at in studies with longer duration. Also, what happened to young healthy Kevin, may not be typical for older subjects, women, or those with excess weight or diabetes. Nevertheless, the study does show that even… Read More »

Does More Sleep Increase Physical Activity in Kids?

Sleep (or rather the lack of it) is increasingly implicated as a major societal and biological “root cause” of obesity. Regular readers will be familiar with previous posts on how sleep deprivation affects appetite and energy metabolism. Now, a study by Canadian Obesity Network bootcamper Michelle Stone and colleagues from the University of Toronto, publish a paper in Preventive Medicine suggesting that kids who reach recommended sleep levels throughout the week are more physically active than kids who don’t. This study looks at the relationship between physical activity (accelerometry) and reported sleep (parents) in about 850 kids. The main finding of the paper is that on weekdays, children who slept the least (<9 hours) were more overweight/obese and less active in terms of overall intensity than those attaining ≥10 hours. Furthermore, weekday-weekend sleep regularity mattered in that overall intensity was higher amongst kids maintaining recommended sleep (>9 hours) compared to those engaging in weekend-catch-up-sleep. Thus, the authors suggest that appropriate weekday-weekend sleep (regularity) may supports healthy activity and should be an important health-promoting strategy. Although studies like this do not prove causality, they certainly fit nicely with the rapidly growing body of evidence suggesting that lack of sleep may well be an important “root cause” of the obesity epidemic. Perhaps time to bring back those afternoon naps? AMS Edmonton, Alberta Stone MR, Stevens D, & Faulkner GE (2012). Maintaining recommended sleep throughout the week is associated with increased physical activity in children. Preventive medicine PMID: 23201000 .

Not enough sleep? Why you may be getting fatter and sicker

Studies have shown that people who don’t get enough sleep consume extra calories, often in the form of unhealthy snacks, says Arya Sharma

Inadequate sleep can lead to obesity, study suggests

And there’s a third factor at play, suggested Dr. Arya Sharma, who holds a chair in obesity research at the University of Alberta in Edmonton…“We’ve … known for a long time that people who don’t get enough sleep tend to be less physically active during the day,” Sharma said.