Newsletter #055

Welcome to the latest edition of the humanOS newsletter! Here is where we share our work, and the various studies and media that captured our attention this week. 🤓

• Dan Pardi: Sleep Hacks for Sleep Deprived Moms. Via Momlight.

Researchers analyzed data on supplement use and incident cardiovascular events from 466039 participants in the UK Biobank study. Glucosamine use was associated with a 15% reduced risk of total cardiovascular events, and a 9-22% lower risk of coronary heart disease, stroke, and CVD death, compared with no use. This relationship remained after adjusting for age, sex, body mass index, race, lifestyle factors, dietary intakes, drug use, and other supplement use.

Fourteen healthy men (who didn’t exercise regularly) were assessed at baseline (no exercise) and during an exercise condition (a 40-min aerobic workout at 40% of maximal oxygen intake, four times between morning and early evening). After exercise, the researchers observed a 33% increase in slow-wave sleep, as well as increases in slow-wave activity, the fast-sigma power/slow-wave activity ratio, as well as subjective sleep depth and restorativeness the following morning. Regression analysis identified increased nocturnal distal-proximal skin temperature gradient during sleep after exercise as a factor in the increase in slow-wave activity. Check out this blog to learn why boosting slow-wave sleep is a very good thing.

Fifty athletes enrolled in the ROTC were randomly assigned to either maintain habitual sleep schedules (controls), or to undertake seven habitual sleep nights, four nights of sleep extension, then four nights of habitual sleep. During the intervention, the experimental group increased mean sleep time by ~1.36 hours, and showed immediate performance benefits in psychomotor vigilance, executive functioning, standing broad jump distance, and motivation levels. Benefits on motor performance remained evident four days after the resumption of habitual sleep schedules.

Researchers examined a rat model of obstructive sleep apnea. In these animals, systolic blood pressure rose over the course of 14 days, which was linked to a 48% decrease in acetate concentration in the cecum. The researchers administered probiotics and prebiotics, which not only abolished the rise in blood pressure but also restored acetate concentrations. To further examine this relationship, the researchers infused acetate into the cecum. This intervention also prevented OSA-induced hypertension, suggesting that metabolites from the gut microbiota may play a key role in blood pressure regulation in this context.

Researchers recruited 32 lean healthy participants. The subjects underwent fMRI while performing a value-based decision-making task with snack food and trinket rewards. This was done following 1) a full night of habitual sleep, and 2) a night of sleep deprivation. Participants were willing to spend more money on food items only after sleep loss. Furthermore, the fMRI revealed a food-reward-specific upregulation of hypothalamic valuation signals and amygdala–hypothalamic coupling. This suggests that weight gain associated with inadequate sleep may be mediated by hedonic factors.

Ginny says: The amino acid glycine has been shown in some studies to accelerate sleep onset and improve sleep quality - and even augment cognitive performance the next day. Why? Remarkably, it is thought that it achieves these effects by triggering changes in body temperature. Glycine, in the right dose, increases blood flow to the extremities, which in turn elicits a drop in core body temperature (for a more detailed explanation of how thermoregulation influences sleep, check out this blog). Pretty cool. Glycine may do other good stuff too - for instance, a recent rodent study showed that glycine supplementation extended lifespan. I like to use three grams right before bed, to match what has been used in studies, and I usually just add it to my late night tea (it tastes really sweet, hence the name!)

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