Newsletter #039: Blood Sugar Regulation, Sleep Deprivation, and the Effects of Sitting on Life Expectancy 🩸
Hello Friends!
Welcome to the latest edition of the humanOS newsletter! Here, we’ll share our work, plus some of the cool studies and media that we reviewed this week and that found their way onto our social media channels. 🤓
This Week’s Research Highlights
🍔 Salivary amylase gene (AMY1) copy number is associated with obesity in Mexican children and adults.
Researchers recruited 921 children (485 normal weight, 436 with obesity) and 920 adults (536 normal weight, 384 with obesity), and estimated their AMY1 copy number. They also performed gut microbiota analyses on a sample of the participants. Low AMY1 copy numbers were significantly more frequent in obese than in normal-weight individuals. Additionally, a higher AMY1 copy number was associated with a high prevalence of Prevotella in the gut - a microbial genus thought to be metabolically favorable.
😪 Sleep deprivation and poor-quality sleep may increase cardiovascular risk
Researchers assessed sleep patterns and cardiovascular health in 3974 bank employees. They found that subjects who slept less than six hours per night were 27% more likely to have atherosclerosis (identified via 3-D heart ultrasound and cardiac CT scans), compared to those who slept 7-8 hours. In addition, individuals found to have poor sleep quality (fragmented, less deep sleep) were 34% more likely to have atherosclerosis, compared to those with good sleep quality.
🚶 Just spending less time sitting and more time moving can extend your life.
Researchers had 7,999 subjects wear activity monitors to capture the amount and intensity of physical activity they engaged in while awake. Upon tabulating the death rate of participants ~5.5 years later, the researchers found that replacing 30 minutes of sitting with 30 minutes of low-intensity physical activity lowered the risk of early death by 17%. Swapping 30 minutes of sitting for 30 minutes of vigorous activity was twice as effective - cutting the risk of early death by 35%.
😴 Sleep restriction may accelerate DNA damage.
Researchers observed 49 healthy doctors who had their blood analyzed at different time points. On-call doctors who had to work overnight exhibited lower DNA repair gene expression and more DNA breaks. And it didn’t take long for effects to become evident - just a single night of inadequate sleep was enough to produce increased DNA damage and reduced repair.
Videos We Loved This Week
- Randolph Nesse: Why We Get Sad: How Evolution Makes Sense of Emotional Disorders. Via EPSIG UK.
- Steven Blair: Physical Inactivity: The Biggest Public Health Problem of the 21st Century. Via Exercise is Medicine Canada @ Queen's University.
New humanOS Content
- Blog: An Orderly Way to Better Blood Sugar Regulation. By Greg Potter.
This week on the blog, Greg discussed a fascinating study, which examined a fairly novel way that people with poor blood sugar regulation (prediabetes) might be able to improve their glucose tolerance. You are probably pretty familiar with how certain attributes of food (fiber, polyphenols) as well as the macronutrient composition can affect blood sugar response. But did you know that the order in which you consume different foods might also make a difference? Researchers tested this by having participants with prediabetes consume either 1) carbs first or 2) protein + salad first. The results were striking - in fact, the size of the difference was comparable to that of certain antidiabetic drugs. To find out what happened, check out the blog!
Media Featuring humanOS
- Greg Potter: Morning Larks and Night Owls: the Biology of Chronotypes. Via Nourish Balance Thrive.
- Dan Pardi (contributor): Can exercising too close to bedtime affect my sleep? Via True Health Initiative.
The humanOS Bookshelf
Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose. By Deirdre Barrett.
Ginny says: Birds are often lauded for their profound investment in their offspring. But European cuckoos are a major exception to this (watch this video!). These birds are noted for engaging in brood parasitism - meaning that they intentionally lay their eggs in the nests of other birds, enabling them to skip the hard work of parenthood entirely. How do they get away with it? The baby cuckoo is typically more compelling (cuter, perhaps?) than the actual biological offspring - larger, louder cries for food, bright red gaping mouth, etc. You see, the cuckoo exploits instinctual cues that draw the attention of the parent birds, and this comes at the expense of the health of the other hatchlings. Researchers like Niko Tinbergen similarly found that birds preferred brighter, bigger eggs - to the point of embracing artificial eggs devised by scientists that were comically massive, bigger than any seen in nature. This has since been characterized as a supernormal stimulus - an exaggerated version of a stimulus that evokes a naturally evolved response tendency.
The truth is that humans are just as susceptible to this. In this book, evolutionary psychologist Deirdre Barrett argues that our entire lives have been furnished around supernormal stimuli. Technology can exploit our instincts in remarkable ways - think of movies, video games, social media, pornography, and other media. Meanwhile, our brains have not evolved to deal with these very new changes to our environment. While it is not the focus of this book, food is another rather obvious example of this phenomenon. We know, for instance, that foods that are high in both carbohydrate and fat (a combination that is rare in natural foods but frequent in manmade hyperpalatable foods) are unusually rewarding, and their nutritional content is not accurately conveyed to the brain, possibly leading to overeating. I think it is easy to argue that supernormal stimuli play a role in the obesity epidemic, and perhaps in other challenges that face us. This is a thought-provoking book that might make you view the world around us and your own life in a whole different light.