Newsletter #193 - Sleep & Biological Aging 🧬😴
Good morning, humanOS friends! This week, we decided to take a look at recent research examining how sleep influences the aging process.
A singular essential purpose for sleep remains unknown. However, we do know that sleep functions as a restorative process, both for the brain and for the rest of the body. For example, endogenous antioxidant systems become more efficient while we are asleep, and metabolic waste products of neural activity are cleared from the brain at a faster rate.
Thus, you would certainly expect that disruptions to this window of opportunity for repair and restoration could lead to increased accumulation of cellular damage, decline in tissue function, and ultimately to accelerated physiological aging. And indeed, that is exactly what we see. Below are a few studies examining how the hallmarks of aging are influenced by sleep loss. 👇🏽
This Week's Research Highlights
🥱 Sleep loss in new mothers is linked to accelerated biological aging.
Researchers at UCLA followed 33 mothers during their pregnancies and over the first year of their babies’ lives. The women provided blood samples, which were used to estimate the rate of biological aging (as opposed to chronological age) by measuring changes in DNA methylation, a method that is uncannily effective at predicting how long someone will live. The researchers found that the biological age of mothers who slept less than 7 hours per night (at the six-month mark) was 3-7 years older, compared to those who recorded 7 hours of sleep or more. First author Judith Carroll noted, ““We found that with every hour of additional sleep, the mother’s biological age was younger.”
👵🏽 Just one night of partial sleep deprivation activates cellular pathways associated with aging.
A group of 29 older adults spent four nights in a sleep lab at UCLA. After the first night (meant as an adaptation night to sleeping at the lab), they had an uninterrupted night of sleep. Then, on the third night, subjects were kept awake from 11pm-3am, then permitted to sleep only from 3am-7am. Blood samples, collected each morning, revealed that sleep loss had increased gene expression patterns in white blood cells associated with senescence. Senescent cells accumulate with age, and tend to promote a state of chronic inflammation, which has been implicated in many of the hallmarks of age-related diseases. Some intriguing research has shown that selectively removing senescent cells may actually reverse some of these conditions - check out this podcast for more information on that.
🧬 People who sleep fewer than five hours per night have shorter telomeres.
Researchers looked at sleep tracking data (acquired via Fitbit and questionnaire responses) from 482 healthy volunteers in Singapore, who were also comprehensively profiled for cardiovascular risk markers. The research team determined, unsurprisingly, that shorter sleep was associated with higher BMI, total cholesterol, and resting heart rate. A subset of the cohort also underwent whole-genome sequencing, and the researchers found that people who slept fewer than 5 hours a night had significantly shorter telomeres, compared to those who slept 7 hours or more. Telomeres are structures at the ends of chromosomes, which help keep chromosomes from sticking together or fraying (sort of like the caps at the ends of shoelaces). They tend to accumulate damage over time due to oxidative stress, which causes them to shorten with age, and this shortening is thought to play a role in the aging process. Premature telomere shortening is linked to earlier onset of age-related disease, as well as earlier death from all causes.
Random Trivia & Weird News
📚 The record for the most overdue library book is 288 years.
A book on the Archbishop of Bremen was borrowed from Sidney Sussex College by Colonel Robert Walpole in 1667–68. It was finally returned in 1956.
No fine was exacted for the overdue return.
Podcasts We Loved This Week
- Nathan Bryan: Role of nitric oxide in human health. Via Sigma Nutrition.
- Davide Castelvecchi: Science in 2022 - what to expect this year. Via Nature Podcast.
Products We Are Enjoying
Nature Made Melatonin Gummies
If you’re having a hard time getting back into a regular sleep schedule, or you’re fighting jet-lag, this can really help you to realign your circadian rhythm. But it’s important to source melatonin carefully, because quality control for over-the-counter supplements can be really questionable.
In one study, researchers systematically analyzed the actual melatonin content in 31 supplements purchased from groceries and pharmacies, and they found that melatonin content varied from −83% to +478% of labeled melatonin, and 70% had a melatonin concentration that was less than 10% of what was claimed! That’s why you want to make sure to get a supplement that is independently lab-tested, like Nature Made. As an added bonus, this brand is super easy to find in stores.
humanOS Catalog Feature of the Week
Body Timing and Health
In this course, we explain how our internal clocks respond to light, and how the master clock synchronizes peripheral clocks in tissues throughout the body. He also describes the processes through which sleep is regulated, how clock genes interact with each other to govern our circadian function, why some of us are “larks” and some of us are “doves,” and much more. Tons of good info for those of you who want to take a deeper dive into the biology of circadian rhythms, but without having to invest a whole lot of time into the endeavor.
To that end, we would also encourage you to refer to our How-to Guides for Smart Daily Light and for Chrononutrition, so you can optimize your light exposure patterns and your food timing respectively for ideal circadian alignment.
Thanks, as always, for reading, and we'll see y'all again next week!