There were several new studies from the past few weeks supporting the importance of sleep for both general health and body weight. According to a study in the Journal of Clinical Sleep Medicine (December, 2007), adults with chronic health problems like heart disease and diabetes that reported less than 7 hours of sleep each night were 3 times more likely to be obese than those who got 8 or 9 hours of sleep. Prior studies have found that sleep deprivation boosts levels of the appetite-stimulating hormone ghrelin, while lowering levels of the appetite-suppressing hormone leptin, in addition to promoting a sluggish metabolism by decreasing insulin’s effectiveness. A second, startling report from the Proceedings of The National Academy of Sciences (December, 2007) found that poor sleep quality in young adults, specifically failing to sleep deeply for just 3 nights in a row, had the same negative impact on the hormone insulin’s effectiveness as gaining 20 to 30 pounds! (Poor insulin activity a.k.a insulin resistance turns your fat cells into fat magnets while dramatically increasing your risk of heart disease and type 2 diabetes.) Stated another way – 3 nights of disrupted sleep gave the young adults in this study the metabolism of people 3 times their age. This was the first study to link poor sleep quality with an increased risk of diabetes and has huge implications for public health as sleep duration and quality are at an all-time reported low and, type 2 diabetes has become the proverbial “runaway train.”
Consistently, studies have found that 7-8 hours of sleep a night for adults is optimal. Both too little and too much can boost your risk of death. A recent Dutch study of 8000 adults ages 35-55 followed for several years found that those who reduced their nightly sleep below 6-8 hours per night from the start of the study experienced a 110% excess risk of cardiovascular-related death. Those who increased their sleep duration beyond 7-8 hours from the start of the study had a 110% excess rate of non-cardiovascular death (Sleep, December 2007)
Kids are susceptible too when it comes to poor sleep and poor health. The journal Pediatrics (November 2007) reported that 6th graders who averaged less than 8.5 hours of sleep a night had a 2-fold greater obesity rate than their counterparts who slept more than 9.25 hours a night. Investigators reporting in the journal Sleep (January 2008) found that amongst 591 seven year olds, those who got the least sleep had a three fold higher risk of being overweight or obese in addition to more emotional volatility. As in adults, adequate sleep is required for both a child’s physical and emotional health. The American Academy of Sleep Medicine recommends that preschool children get 11-13 hours of sleep a night and that school-aged children get 10 to 11 hours per night.