Newsletter #65: Why Good REM Sleep Might Help You Recover from Traumatic Karaoke Experiences 🎤
Welcome to the newest edition of the humanOS newsletter! Here, as always, is where we share our work, plus the various studies and media that captured our attention this week. 🤓
This Week’s Research Highlights
Researchers compared skeletal muscle of germ-free mice (no gut microbiota) to that of control mice that had a gut microbiota (free of pathogens). Germ-free mice had atrophied muscle, decreased expression of IGF-1, and reduced transcription of genes associated with skeletal muscle growth and mitochondrial function. Gut microbiota transplantation from the pathogen-free control rodents into germ-free mice resulted in an increase in skeletal muscle mass, a reduction in muscle atrophy markers, improved oxidative metabolic capacity of the muscle, and elevated expression of the neuromuscular junction assembly genes Rapsyn and Lrp4.
Researchers analyzed data from a series of cross-sectional nationally representative surveys on adults from the National Health and Nutrition Examination Surveys from 2007 to 2016. The data revealed that time spent sitting increased from 5.7 hours a day in 2007-2008 to 6.4 hours a day in 2015-2016. The increase in sedentary behavior was seen in nearly every major subgroup of the U.S. population. There was no substantial change in physical activity levels.
🤯 Disrupted REM sleep may make it harder to process emotional memories, and ultimately bounce back from embarrassing experiences.
Okay, this is one of the weirdest study designs I have ever seen (in a good way). Researchers had volunteers sing while wearing muffled headphones, making it nearly impossible for them to sing well. Thereafter, the subjects had to listen to the recording of themselves singing horribly. While listening, electrical activity in the amygdala (visualized via fMRI) was ramped up in response. Participants then spent the night in a sleep lab. EEG showed that participants REM sleep patterns differed immensely. Finally, the subjects endured another cringe session listening to the song recording. Those who had good REM sleep showed less reactivity in the amygdala, while those who experienced interrupted REM showed a similar response. We may need good consolidated REM sleep in order for our amygdalae to adapt to challenging or painful experiences.
🧖♀️ Recovery from sauna bathing favorably influences the cardiac autonomic nervous system by modulating heart rate variability.
93 middle-aged participants were exposed to a single sauna session (30 minutes long; temperature 73 °C). Data on resting heart rate and HRV variables were collected before, during, and after the session. Resting heart rate rose during the sauna, and then dropped to 68 bpm at the end of recovery (down from 77 bpm before entering the sauna). During the cooling down period from sauna bathing, HRV increased, suggesting a dominant role of parasympathetic activity and decreased sympathetic activity of cardiac autonomic nervous system.
New humanOS Content
In a recent study, Miller and his team randomly assigned 53 participants to consume either placebo or metformin for 12 weeks, while completing a supervised aerobic exercise program. Now, this exercise regimen elicited measurable improvements in blood sugar control, insulin sensitivity, and aerobic fitness for the volunteers, much as you would anticipate when sedentary individuals adopt a program of physical activity. Nothing unusual there.
But when the groups were compared, some meaningful and troubling differences emerged, suggesting that metformin and exercise may not play well together, and we might want to think twice before offering the drug to healthy (non-diabetic) people to combat aging. Check out the interview to learn more about the study, and its potential implications!
Podcasts We Loved This Week
- Lyle McDonald: N.E.A.T. vs Constrained Total Energy Expenditure. Via The Muscle Engineer Podcast.
- Irina & Michael Conboy: Tissue Repair and Stem Cell Regeneration. Via STEM-Talk.
- Keith Flaherty: Deep dive into cancer— History of oncology, novel approaches to treatment, and the exciting and hopeful future. Via Peter Attia Drive.
Products We Are Enjoying
Ginny says: If you are making summertime smoothies (like me), this stuff is like magic. I like to add a tiny amount (like ¼ teaspoon) to make the texture smoother and creamier. It’s especially helpful for smoothies that contain a ton of greens or berries. Remember that a little goes a long way with this stuff.