Newsletter #023

Welcome to the latest edition of the humanOS newsletter! This is where we share our own work, and the interesting research and media that we stumbled upon this week.  🤓

First of all, we are excited to announce that we are launching a series of quick How-to Guides for our Pro users, which will encompass various areas of health performance. We think these tools will function as an excellent complement to the educational content we have worked so hard to develop and will provide a useful shortcut for folks who just want to know what to do.

The first three emanate from the Ideal Weight Program, developed with Stephan Guyenet, and the last one is a science-based guide to constructing healthy smoothies. Here they are!

You will need to log in to your Pro account first to access them. And there are more on the way in the relatively near future, so stay tuned  😃

Meanwhile, this week on humanOS Radio, Dan interviewed Dr. Mimi Shirasu-Hiza from Columbia University. Her lab does some really cool work with circadian mutants of fruit flies, and one of her latest publications, which she and Dan discuss on the podcast, is downright ground-breaking. Here’s why: Sleep is kind of an enigma. Despite decades of meticulous research, the essential purpose of sleep has remained unclear.

To help unravel this mystery, Mimi and her colleagues examined a diverse group of fruit flies that carry different genetic mutations, all of which result in a substantial reduction in total sleep. They hypothesized that these short-sleeping fruit flies might all share a common physiological defect due to that sleep loss. Through an elegant series of experiments, Mimi and her team did indeed uncover a shared defect, which just might point to a potential core function of sleep. Definitely check out the interview on our blog to learn more!

Researchers at the University of São Paulo divided rats into two groups. One was put on an exercise training program, the other remained sedentary. Afterwards, the rodents had sciatic nerve ligation surgery, which rendered them unable to use their legs. This typically leads to rapid muscular atrophy. However, the group of rats that exercised showed less aggressive muscular dysfunction than their sedentary counterparts. When the researchers analyzed the muscle tissue, they found that exercise had upregulated autophagy — the cellular process through which damaged proteins are identified and eliminated. This meant that dysfunctional proteins were being eliminated, enabling the muscle to retain its contractile properties longer. Principal investigator Julio Cesar Batista Ferreira said, "Daily exercise sensitizes the autophagic system, facilitating the elimination of proteins and organelles that aren't functional in the muscles. Removal of these dysfunctional components is very important; when they accumulate, they become toxic and contribute to muscle cell impairment and death.”

Researchers at UCSF recruited 279 women who were expecting their first child. They collected data on depressive symptoms, as well as the amount of daylight that they experienced during the final trimester of pregnancy. The researchers found that women whose final trimester coincided with decreasing daylight hours (from August to November), depression scores were highest (35%), and symptoms continued to be more severe after the birth of their babies. The lowest risk of depression was found in women whose final trimester occurred in seasons with longer daylight hours (think Spring or Summer in the northern hemisphere). The findings suggest that increasing light exposure, like with a light box or going outside, could protect the mental health of women in late pregnancy and in the postpartum period.

Researchers in France recruited 101 undergraduate students and randomly assigned them to one of two experimental conditions. One group performed 15 minutes of jogging, and the other engaged in 15 minutes of relaxation (control). Before and after the interventions, all participants were given a battery of cognitive tests. The researchers found that after performing the bout of exercise, subjects were able to complete a test of perceptual speed/visual attentional control faster, with no such improvement shown in the control group. This appeared to be mediated by a feeling of increased energy in the jogging group.

Dan says: The amino acid glycine has been shown in some studies to speed up sleep onset and improve sleep quality, and even augment cognitive performance the following day. Sounds good, right? Interestingly, it seems to do this, at least in part, by triggering changes in body temperature. Glycine increases blood flow to the extremities, which in turn elicits a drop in core body temperature (check out this past blog to learn more about how thermoregulation influences sleep). I try to take 3 grams (close to a teaspoon) before bed.

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