Sleep, Obesity, and Exercise

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by Marion Webb It wasn’t that long ago when Americans paralleled professional success with getting as little sleep as possible. Today, many have come to realize that chronic sleep deprivation isn’t just bad for business, it’s detrimental to your health. Suddenly the same doctors who have long warned that a chronic lack of sleep and sedentary living can lead to serious health consequences, including weight gain, obesity and associated chronic diseases, such as heart disease and diabetes, are getting air time and media attention. Why? Look around: With 133.6 million overweight or obese adult Americans and a first generation of children who are unlikely to outlive their parents due to complications related to overweight and obesity, doctors are hopeful that the importance of sleep and correlations to physical activity and a healthy diet will finally hit mainstream and evoke a widespread lifestyle change. How Much Sleep Do We Need? Scientists have long said that sleep needs and patterns can vary significantly from one individual to another. While there is no magic number, the National Sleep Foundation cited two studies suggesting that healthy adults have a basal sleep need (the amount of sleep our bodies need for optimal performance) of seven to eight hour a night, but due to unresolved sleep debt (sleep lost due to bad sleeping habits, sickness, staying awake or waking up during the night), people spend their days feeling sleepy or less alert at times. Can you Bank Snooze? Studies focusing on paying off sleep debt by either making up for lost sleep later or trying to sleep ahead per se, have shown mixed results. One study at the Walter Reed Army Institute of Research in 2003 found that recovery sleep did not fully reverse declines in performance on test of reaction times and other psychomotor tasks. During the study, scientists examined the cognitive effects of a week of poor sleep followed by three days of eight hours of sleeping each night, according to a New York Times article on Nov. 3, 2009. In a similar study conducted at the Karolinska Institute in Stockholm, subjects who slept four hours a night over five days, and then recovered by sleeping eight hours a night over the following week, still showed slight residual cognitive impairments a week later, though they reported not feeling sleepy. However, another study by the Walter Reed Army Institute of Research, found that people recovered much more quickly from a week of poor sleep when it was preceded by a banking week up to 10 hours of shuteye each night. Newer research findings, presented on March 21 at the annual meeting of the American Association for the Advancement of Science in San Diego, found that young adults who slept 90 minutes after lunch had greater learning power compared to those who didn’t nap. The study, which was conducted at the University of California, Berkeley, recruited 39 healthy young adults and divided them into two groups. Those who slept for 90 minutes between two learning sessions (one at noon; another at 6 p.m.) improved their scores by 10 percent on average after sleeping, suggesting that afternoon naps aren’t just good for toddlers. However, the National Sleep Foundation, reported findings that four to five hours of sleep every night certainly isn’t enough and can lead to serious physiological and neurobehavioral consequences. Getting inadequate amount of sleep has been linked to:
  • Increased risk of motor vehicle accidents
  • Increase in body mass index – a greater likelihood of obesity due to an increased appetite caused by sleep deprivation
  • Impaired glucose tolerance and an increased risk of diabetes and heart problems
  • Increased risk for psychiatric conditions including depression and substance abuse
  • Decreased ability to pay attention, read signals or remember new information
Is Exercise Before Bedtime Detrimental to Sleep? When it comes to healthy living, getting enough sleep and exercise go hand in hand. However, scientists remained mystified over why mild exercise can be invigorating, but strenuous endurance exercise sometimes leaves people groggy and wanting to sleep more. For most people, who exercise regularly, but aren’t endurance athletes, scientists recommend completing their workouts at least three hours before bedtime to allow the body to become sleepy. Mild exercise raises the body’s core temperature, so it can take a few hours for the temperature to drop, signaling the body to sleep. Many endurance athletes however, often have the opposite problem. Their exercise sessions can leave them tired and sleepy, so it comes to no surprise that many need more sleep than non-athletes. One possibility, according to an article in the New York Times, suggested that endurance training prompts muscles to release two cytokines, interleukin 6 and tumor necrosis factor alpha, which are the same cytokines that are released when people have a cold or an infection, which is why people sleep so much when they are ill. Hence, repetitive long and hard training can make you so sleepy that more than eight hours are often needed to feel fully recovered. Sleeping Your Way to Obesity A lack of sleep can trigger the production of cortisol, a stress hormone, and an increase of insulin production, which promotes fat storage and is associated with weight gain. Reduction of leptin and higher levels of ghrelin may result in cravings for sweet foods and overeating. A study by the University of Chicago in young adults found that restricting sleep to four hours a night for a week brought on the same glucose and insulin levels characteristics that are seen in diabetics, which the investigator cautioned can be a pathway to obesity. Another study conducted in 2006 by the University of Warwick Medical School found that a lack of sleep can as much as double the risk of obesity in adults and children. Children and Sleep The National Sleep Foundation suggested that children need much more sleep than adults to be well-rested: Preschoolers aged 3 to 5 need 11 to 13 hours of sleep while school-aged children up to age 12 need about 10 to 11 hours of sleep. Ever wonder why your teenager refuses to go to bed before 10 p.m. or just can’t get out of bed in the morning? According to the sleep foundation, teenager’s circadian rhythms are geared toward staying up later in the evening and waking up later in the morning. Adolescents typically need nine hours of sleep a night to function well. Granted, in this digital age, many Americans have a tough time shutting off their laptops and iPods or stay connected to their social networking sites until the wee hours. Just think how much more productive and less grumpy we all could be by making sleep a priority. So here’s my tweet to you for good health: Sweet dreams. Tips for Good Sleep
  • Establish consistent sleep and wake schedules, even on weekends
  • Create a regular, relaxing bedtime routine such as soaking in a hot bath or listening to soothing music
  • Exercise regularly and complete the workout at least three hours before bed time
  • Sleep on a comfortable mattress and pillows
  • Create a sleep-conductive environment that is dark, quiet and preferably cool and comfortable
  • Use your bedroom for sleep and sex (avoid watching TV in bed, using a computer or reading)
  • Finish eating at least 2-3 hours before bedtime
  • Avoid caffeine and alcohol close to bedtime
  • Stop smoking
  • Make sleep a priority
Marion Webb is the managing editor for the American Council on Exercise and is an ACE-certified Personal Trainer and an ACE-certified Group Fitness Instructor.

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