Newsletter #91: Overcoming Jet Lag & Why Stress Gives You Gray Hair 🧑🦳
Hello Friends!
Welcome to the Super Bowl edition of the humanOS newsletter! 🏈 Below is our work, plus the assorted studies and media that captured our attention this week. 🤓
This Week’s Research Highlights
👨🦳 Stress may actually turn hair gray, via the sympathetic nervous system.
There is a lot of anecdotal evidence pointing to an association of stress with gray hair, but plausible biological mechanisms that might drive this phenomenon have been lacking...until now. Researchers exposed mice to various stressors at different phases of hair growth. They found that the stress caused depletion of melanocyte stem cells from their hair follicles (melanocytes are the cells that determine hair color). This eventually resulted in the loss of pigment, and patches of white hair on the rodents. When the researchers probed more deeply, they discovered that melanocyte stem cells express β2-adrenergic receptors, which respond to noradrenaline. Activation of the sympathetic nervous system leads to a release of noradrenaline, which produces a cascade of cellular reactions that lead to the depletion of melanocyte stem cells. Knocking out the adrenergic receptors in this region prevented stress-induced hair graying.
🐶 Owning a dog is linked to reduced mortality, with even greater benefits for those who live alone.
Researchers assessed pooled data from ten studies including a total of 3837005 participants. The meta-analysis revealed that dog ownership was associated with a 24% risk reduction for all-cause mortality as compared to non-ownership. When the analysis was restricted to studies evaluating cardiovascular mortality, dog ownership conferred a 31% risk reduction for cardiovascular death. Another study provided further support to this finding. Researchers examined data from the Swedish National Patient Register to identify patients presenting with either a heart attack or stroke (n = 336313). Information was available for mortality, cause of death, dog ownership, household members, and other relevant factors. Dog ownership reduced mortality in patients living with partners and children, but benefits were particularly pronounced for those who lived alone. The researchers found that ischemic stroke survivors living alone who had dogs had a 27% reduced risk of death, compared to those who did not, and survivors of a heart attack living alone with dogs experienced a 33% reduced risk of mortality.
🥱 Prevalence of inadequate sleep seems to be going up, and the problem is hitting some of our most critical workers the hardest.
Researchers analyzed data from more than 150000 employed adults between 2010 and 2018. They found that the rate of inadequate sleep (defined here as 7 hours or less; of course some folks may not need that much) had risen from about 31% in 2010 to 36% in 2018.
Professions with the highest levels of poor sleep, unsurprisingly, included the police and military (50%), healthcare support occupations (45%), transport and material moving (41%), and production occupations (41%).
Podcasts We Loved This Week
- Adam Konopka: On metformin’s effects on healthspan and lifespan. Via STEM-Talk.
- Paul Bloom: On the tragic death of Kobe Bryant, and the paradoxes of moral responsibility. Making Sense with Sam Harris.
- Christopher Hendon: Using chemistry to get the perfect cup of coffee. Via Science Friday.
Products We Are Enjoying
Bada Bean Bada Boom roasted fava beans.
These crunchy seasoned beans are excellent sprinkled on soups or salads (a good healthy alternative to croutons), or just eaten by themselves. They contain seven grams of protein and five grams of fiber, so for a packaged snack food they are very solid from a nutritional standpoint. Obviously, avoid if you have a genetic condition that contraindicates the consumption of fava beans.
