Newsletter #164: The Myriad Consequences of Sleep Loss 😴
Hello again humanOS friends!
This week, we stumbled upon some very useful research on the impact of sleep and circadian alignment on some under-appreciated aspects of health, including athletic injuries and the adaptive immune system.

Key takeaways:
🔹 Inadequate sleep may increase your risk for injury;
🔹 Going to school early likely means less sleep for grade school kids;
🔹 Short sleep may impair effectiveness of vaccines (or even abolish their benefit entirely).
To get all the details, scroll on down 👇
This Week’s Research Highlights
⛹️ Short sleep is associated with significantly greater risk of injury.
Researchers surveyed a group of student athletes and their parents at a combined middle/high school about training practices and their habitual sleep. Their responses were then correlated with injury records obtained from the school’s athletic department. The researchers found that insufficient sleep was one of the two strongest predictors of sports injuries in these adolescents. Athletes who slept less than eight hours per night were 1.7 times more likely to have had an injury, compared to those who slept at least eight hours. Players reporting six hours of sleep per night experienced four times more injuries, compared to those getting nine hours of sleep.
📓 Later school start times means significantly more sleep for students.
Researchers measured and compared sleep parameters in middle school students attending either a morning (7:00-12:00) or an afternoon (12:30-17:30) school shift. Morning students got one hour and forty-five minutes less sleep nightly, compared to their afternoon counterparts, and even taking naps failed to overcome this sleep deprivation. Furthermore, morning students slept significantly longer on weekends (over two hours longer), suggesting that they were experiencing social jetlag, a pattern that was not exhibited by the afternoon students. There were no differences between the groups in evening time spent on media use, leisure, homework, or other activities. The benefits of delayed school schedules and accompanying longer sleep may even extend to academic performance - a similar study examining Seattle public schools found that later school start times were linked to better sleep and higher median grades.
💉 Inadequate sleep may significantly reduce vaccine effectiveness.
Researchers had 83 healthy young adults complete 13 days of sleep diaries. On day three of the study, subjects received the influenza vaccine, and antibody levels were assessed at baseline and then at 1 and 4 months following the vaccination. Shorter sleep duration on the two nights prior to vaccination predicted fewer antibodies at the 1 and 4 month mark, independent of baseline antibodies, age, sex, and generation.

This lines up with a similar study from a while back that found that people who slept fewer than six hours per night were more than 11.5 times more likely to mount a poor antibody response to the hepatitis vaccine, to the point of being wholly unprotected, compared to people who got at least seven hours of sleep. If and when you get vaccinated, make sure to get plenty of rest to give your immune system the best possible chance to do its thing.
Random Trivia Question of the Week
🤔 What creature is thought to have the highest blood pressure in the animal kingdom?
💡 ANSWER
Podcasts We Loved This Week
- Robert Stickgold & Antonio Zadra: A unified theory of dreaming? Via Sleep Junkies.
- Juan Enriquez: How might technology shift our morality? Via Science Friday.
Products We Are Enjoying
Glycine powder
The amino acid glycine has been shown in some studies to accelerate sleep onset and improve sleep quality Interestingly, it appears to do this 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 some other good stuff too - for instance, a rodent study a while back showed that glycine supplementation extended lifespan.
Studies typically use around three grams, which you can easily add to your beverage of choice right before bed. It tastes sweet (hence the name), so it’s not too hard to take.
humanOS Catalog Feature of the Week
Enjoy the weekend, and we'll see y'all next week, same time and place!