For most surgeons their interest in sleep can be summed up by an adage that is commonly repeated in surgical residency. The saying goes, “never stand when you can sit, never sit when you can lay down, never lay down when you can sleep”. Surgical residents in my era spent 5-7 years being chronically sleep deprived. (new rules have recently mandated less hours and more rest for residents). It is surprising to no one that sleep deprivation can have adverse effects on ones physical health. The exact delineation of these adverse effects is still ongoing.
As the blog post listed below, from one of my favorite weight loss blogs, “Dr. Sharma’s Obesity Notes“, reviews a couple of studies dealing with the association of sleep patterns and weight gain. As I have discussed in previous blog posts, there is a large amount of evidence that lack of sleep, irregular sleep, and working the night shift, are all associated with weight gain. As with any association, you can’t necessarily infer causality. Foe example, the fact that playing loud music and keeping their rooms messy is a common association in teenagers, doesn’t mean that loud music causes teenagers to not clean their room. To prove causality, you need to change only one variable and see if the other observation changes. So in our example, you would need to make your teenager turn down the music without mentioning the room and see if they on their own keep their room neater. For those of you who are interested, there is no causality, you have to nag your teenager about both things independently. Stated another way, if all you know is that poor sleep and obesity are associated, you don’t know if poor sleep causes obesity, if obese people don’t sleep well, or if there is some third factor that links the two.
The reviewed studies begin to lend credence to the idea that it is in fact that poor sleep hygiene leads to obesity, and further that improvement in sleep should be a priority for patients trying to lose weight. A multidiseplanary weight loss clinics such as LifeShape probably should start devoting more attention to sleep health as a potential intervention to help patients lose weight.
Regular readers are well aware of the increasing evidence that points to a major role for sleep deprivation in the current obesity epidemic. Indeed, one of the most evident societal changes coinciding with the epidemic spread of excess weight is the significant reduction in sleeping hours – in both kids and adults.
Now a study by Orfeo Buxton and colleagues from Harvard University, published in Science Translational Medicine, shows just how profoundly sleep restriction and disruption of sleep cycles can affect your metabolism.
The experiments were designed to tested the hypotheses that prolonged sleep restriction with concurrent circadian disruption, as can occur in people performing shift work, impairs glucose regulation and metabolism.
Healthy adults were recruited to spend at least five weeks under controlled laboratory conditions in which they experienced an initial baseline segment of optimal sleep, three weeks of sleep restriction (5.6 hours of sleep per 24 hours) combined with circadian disruption (recurring 28-hour “days”), followed by 9 days of recovery sleep with circadian re-entrainment.
Not only die sleep restriction with concurrent circadian disruption markedly decrease participants’ resting metabolic rates but these interventions also increased plasma glucose concentrations after a meal, due to reduced pancreatic insulin secretion.
Nine days of recovery sleep normalized all of these changes.
Interestingly enough, a recent study by Korean researchers, published in the Journal of Sleep Research, looking at the relationship between sleeping patterns and body weight in almost 1,000 school children (48.2% boys) aged 10 or 11 found that, after adjusting for relevant confounding variables (age, sex, breakfast eating, screen time and parental obesity), longer sleep on weekdays and weekends was associated with 30% decreased odds of excess weight.
Perhaps, more importantly (and in line with the Harvard study), kids who slept little during the week but managed to catch up on their sleep deficit on the weekends also had a lower risk of excess weight.
Together these findings support the notion that sleep hygiene may be an important target for intervention in weight management and, at a population level, may well be an issue that may deserve as much attention and discussion as health eating and physical activity.
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