By: Emilie F. Hester, CPT and Larry N. Smith, MD, CPT
There is nothing better than sleeping in on a Saturday morning and getting out of bed when the desire hits us. You roll out of bed feeling refreshed and rejuvenated. Or better yet, getting a 10 minute power nap at your desk, on the couch, or snuggled in bed with baby on your chest. These simple activities reveal how sleep is so important to humans.
This post will discuss the benefits of sleep and the negative consequences of not getting enough sleep. Because sleep is involved with many physiologic systems, insufficient sleep duration and poor sleep quality have been associated with several adverse health outcomes. Separate literature texts have emerged describing some of the negative effects of insufficient sleep duration, sleep apnea, and insomnia. The positive effects of sleep will be discussed as well as it relates to sports and weight loss.
SLEEP EFFECTS ON HEALTH AND LONGEVITY
Mortality: The first report documenting the relationship between sleep duration and mortality risk was published more than 50 years ago.(1) This first study, an analysis of data from the American Cancer Society’s first Cancer Prevention Study of more than one million US adults, found that increased mortality risk was associated with both short (6 hours or less) and long (9 hours or more) sleep duration. Since that time, many other studies have been published, from both large and small cohorts, covering both short and long follow-up periods, from 6 continents. Taken together, this overall pattern of findings, that both short and long sleep are associated with mortality risk.(2)
Weight Gain and Obesity Many studies have found associations between sleep duration, weight gain and obesity. These studies have demonstrated that loss of sleep is associated with increased weight gain over time.(3)
Diabetes and Metabolism Several studies have documented a relationship between insufficient sleep and diabetes risk.(4,5,6,7) A recent meta-analysis showed that insufficient sleep is associated with a 33% increased risk of incident diabetes.(8) These studies are supported by laboratory findings that show that physiologic sleep loss is associated with diabetes risk factors, including insulin resistance, and other diabetes risk factors, such as increased consumption of unhealthy foods. Physiologic studies also show that sleep loss can influence metabolism through changes in metabolic hormones, adipocyte function, and pancreatic beta-cell function.(9,10,11,12,13,14, 15,16)
Inflammation Laboratory studies have shown that loss of sleep is associated with a proinflammatory state, including elevations in inflammatory proteins in the body.
Cardiovascular Disease In addition to increased likelihood of obesity, diabetes, and inflammation, lack of sleep is associated with increased risk of cardiovascular disease. Many studies have found that short sleep duration is associated with hypertension. There is some evidence that habitual short sleep increases likelihood of cardiovascular problems and events.
Neurocognitive Functioning Many studies have examined the relationship between laboratory-induced sleep loss and brain function. These studies show that as sleep time declines, attentional lapses increase, with these impairments becoming cumulative over time. Loss of sleep duration has been shown to cause impairments in working memory, executive function, processing speed, and cognitive throughput. Although some of these effects may be rescued with stimulants such as caffeine, the effects on executive function particularly do not seem to be rescued. Some studies show that reduced sleep time is associated with drowsy driving and occupational accidents.
Mental Health Many studies have shown that short sleep duration is associated with poor mental health. Sleep disruptions are a common diagnostic feature of many mental health disorders. Patients with mood disorders and anxiety disorders frequently experience short sleep duration. Sleep duration has also been identified as a suicide risk factor. In the general population, overall mental health has been identified as the leading predictor of self-reported insufficient sleep.
For the Athlete:
Sleep serves an absolutely vital physiological function and is arguably the single most important factor in exercise recovery. It has been noted that sleeping more is associated with increased recovery. Many athletes and coaches prioritize exercise and seek to obtain the highest quality fitness. However, quality sleep should be part of the foundation of an elite athlete’s routine. Building this vital function into an athlete’s training program must be emphasized. Athletes can train themselves to improve their sleep if they have deficits, which by all measures should translate into improved performance. Therefore, the old saying “you snooze, you lose” should actually read to athletes, “you snooze (more), you win.”(17)
Sleep is a critical component to a healthy body and life style. Loss of sleep is not recoverable but getting into a proper sleep cycle with 6 to 8 hours a night will begin to bring balance to the body's needs. Combining exercise with balanced sleep will control weight, improve mental function, reduce risk for cardiovascular disease and improve exercise tolerance and duration.
Part 4 will discuss ways to get more sleep and have more effective sleep.
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