Short sleep duration and a host of deleterious health conditions for people are linked, increasingly abundant evidence concludes again and again. Now a mechanism to help explain how sleep deprivation is biologically linked to aberrant metabolism, and from there to obesity and type 2 diabetes, has been shown in an Annals of Internal Medicine study. Perhaps this evidence may influence Rick to mend his chronically sleep-deprived ways, as we conclude on PodMed, although I am pessimistic about that particular outcome, especially in light of the fact that he is neither obese or diabetic. On a population basis though, this study may help us get our arms around one factor that may be fueling the obesity epidemic.
In describing this study, I freely admit that I am a bit of a study junkie, having volunteered around our fine institution for a number of clinical investigations, and this is one I would have assiduously avoided. That's because these 7 volunteers, 6 men and 1 woman, with a mean age of 24 years and of normal weight, first had to have a biopsy of their subcutaneous abdominal fat, endure sleep deprivation for 4 nights, then have another biopsy. Yikes! My tolerance for sleep interruption is poor to begin with, and I can only imagine how that would impact on my tolerance for subcutaneous fat biopsy. In any case, thanks to these brave subjects.
Sensitivity to insulin was assessed in the fat cells, or adipocytes, collected via biopsy, using the ability of insulin to increase the phosphorylation of Akt, a critical first step in the insulin signaling pathway, in the cells. Samples from each participant were compared following normal sleep (8.5 hours in bed) for four days and interrupted sleep (4.5 hours in bed) for four days. Phosphorylation required about three times more insulin in the sleep deprived state than in the normal sleep state. The authors state that a reduction in total body insulin sensitivity paralleled this physiologic change. Well. Could this be the linchpin connecting sleep deprivation with that downward slope of obesity, the metabolic syndrome, type 2 diabetes and its host of health consequences? And if so, what can we do about it?
As Rick so aptly points out in the podcast, societally, we're chronically sleep-deprived. In the service of connectedness, multitasking, increased levels of stress, employment conditions and a host of other factors, many if not most of us just don't get enough sleep. There's also the vicious downward spiral of obesity begetting sleep apnea, which then begets more fat accumulation and exacerbated breathing problems while recumbent. What's a person to do? One of my favorite phrases in medicine, "sleep hygiene," needs to be considered. As we recognize our need for sleep, we need to make sure getting enough is a priority, just like exercise or sound dietary choices. The bedroom should be a refuge, with temperature and lighting designed to facilitate sleep. If we're wakeful, we need to get up and go elsewhere rather than toss and turn, and we need to pay attention to what we eat and how much before sleep, avoiding activities that may be overstimulating such as exercise (!), work, computer games and the like. And here's another fav of mine: naps during the workday. Hmmmm.
Other topics this week include the reuse of implantable cardiac devices, also in Annals, multivitamins in cancer prevention and HIV therapy in JAMA, and a new coronavirus in NEJM. Until next week, y'all live well.