Newsletter #043: Food that affects the quality of sleep 🛌🏻 🍅
Hello Friends!
Welcome to the latest edition of the humanOS newsletter! Here, we’ll share our work, plus some of the cool studies and media that we reviewed this week and that found their way onto our social media channels. 🤓
This Week’s Research Highlights
👶🏻 Young children are highly sensitive to the melatonin-suppressing effect of bright light.
Researchers had ten preschool-age children follow a strict sleep schedule for five days. On the sixth day, the children entered a dim light environment (<15 lux) to provide saliva samples at regular intervals (to establish baseline measurements). On day 7, the subjects remained in dim light, then were exposed to a bright light (1000 lux), before returning back to dim light at bedtime. The researchers found that the bright light-induced substantial melatonin suppression (87.6 ± 10.0%). And they stayed low - melatonin levels did not return to even 50% of where they had been in the dim light condition for most children.
🍕 Higher intake of ultra-processed food is associated with higher mortality risk.
Researchers analyzed the reported frequency of ultra-processed food intake (stuff like sugar-sweetened beverages, sweetened milk, sausage or other reconstructed meats, sweetened cereals, and confectionery) from the third NHANES (1988-1994) in a representative sample of 11898 Americans. Over a median follow-up of 19 years, individuals in the highest quartile of frequency of ultra-processed food intake had 31% higher risk of all-cause mortality, after adjusting for demographic and socioeconomic confounders and health behaviors.
☀️ Vitamin D deficiency is associated with insulin resistance.
Researchers examined 90 type 2 diabetes patients and 90 matched controls and took bloodwork to determine metabolic markers and serum 25(OH)D. Vitamin D deficiency was positively associated with insulin resistance, fasting blood sugar, and HbA1c among all participants. Furthermore, participants with severe 25(OH)D deficiency (<10 ng/ml) had 39 times higher odds of having type 2 diabetes. Moderate deficiency (10-19ng/ml) and insufficiency (20–29 ng/ml) conferred 16 times and 13 times higher odds of type 2 diabetes respectively.
🍅 Tomatoes may improve sleep quality.
Researchers had participants consume 250 grams of beefsteak tomatoes every night, two hours before they went to sleep. After 8 weeks, sleep quality (measured via PSQI) had significantly improved and urinary 6-sulphatoxymelatonin levels were 10-fold higher in the tomato group than controls.
🧅 Eating garlic and onions may reduce risk of colorectal cancer.
Researchers recruited 833 patients with colorectal cancer as well as 833 matched healthy controls, and collected dietary information using a validated food frequency questionnaire. The odds of having colorectal cancer was found to be 79% lower in participants who consumed high amounts of allium vegetables, compared to those who consumed low amounts.
Podcasts We Loved This Week
- Matthew Walker: Everything You Know About Sleep is Wrong. Via the Science of Success podcast.
- Chris Smith: eLife episode 38: Boosting your brain. Via eLife.
- Leslie Vosshall: Putting Mosquito-borne Illnesses on a Diet. Via Science Friday.
Media Featuring humanOS
• Greg Potter: Circadian Rhythm: The Science Behind the Best Sleep of Your Life. Via the Collective Insights Podcast.
The humanOS Bookshelf
Why Zebras Don’t Get Ulcers. By Robert Sapolsky.
The physiological stress response is highly conserved across different animal species. Fish, birds, reptiles, mammals, etc all secrete certain hormones (adrenaline and glucocorticoids) that raise heart rate and blood pressure, among other effects. This response is highly adaptive in the face of danger (like, say, if you are a zebra running from a lion on the savannah), and generally short-lived. But humans are unique because although most of us are never confronted with mortal peril like the zebra, we experience chronic stress - mostly because we are intelligent enough to induce this state in ourselves and in each other.
In this book, Dr. Sapolsky explains how prolonged exposure to psychosocial stress affects nearly every organ system - increasing atherosclerosis, suppressing the immune system, shutting down reproduction, disrupting digestion, deranging blood glucose metabolism, etc. Much of Sapolsky’s insights emanate from his decades of research on African baboons in Kenya.
These animals are highly social primates that are generally safe and well-fed but are subject to psychological stress due to interactions with one another. And it turns out that they pay the price for these elevated stress hormones, much like we do. This is a fairly old book (would be cool to see it get another update) but worth a read for sure.
humanOS Catalog Feature of the Week
Sleep and Weight Control
This week, we’d like to highlight one of the courses from the Ideal Weight Program, developed by Stephan Guyenet. Much of the Ideal Weight Program is centered around nutrition, as you would expect, but research has shown that multiple aspects of our lifestyle play an important role in body weight. Sleep is one of the most important, and perhaps most underappreciated.
In this course, Stephan reviews the basics of sleep and circadian rhythms, then zooms in on how insufficient or misaligned sleep specifically influences body fatness. He looks at a few key studies that have examined the impact of altered sleep on food intake, which largely mirror the findings that we described above. But it actually gets even worse - sleep loss can also adversely affect nutrient partitioning, making it harder for you to hold onto muscle! Fortunately, this is for the most part a solvable problem. Stephan covers realistic ways for you to obtain restorative sleep, and hopefully achieve your body composition (and health) goals.