Newsletter #205 - Three Major Benefits of Sleep Extension 💤
Hey friends, hope y’all are happy and healthy! So this week, we are circling back around to the topic of sleep - and why you really should get more of it.
People living in the US, in general, seem to not be getting enough sleep. One study that examined 669 American adults found the average sleep duration in that group was just 6.1 hours. And research suggests that the prevalence of inadequate sleep in the general population has risen in recent years, from 30.9% in 2010 to 35.6% in 2018. The pandemic may have further exacerbated this unfortunate trend.
You might remember a few weeks ago, we looked at how sleep duration affects food intake and energy balance. One particularly compelling study found that overweight adults who successfully increased their nightly sleep by about an hour went on to decrease their daily energy intake by 270 calories, which as you would expect ultimately led to weight loss in that group. Which if you ask me is pretty impressive for an intervention that is basically free and (at least in theory) accessible to everybody.
But the benefits of sleep extension are certainly not limited to weight regulation. If you look at various clinical trials in which participants sleep significantly more than usual, you can find a plethora of physiological benefits, ranging from cardiometabolic health to exercise performance. Scroll on down to learn more 👀
This Week's Research Highlights
🍭 Sleep extension improves blood sugar metabolism.
Researchers recruited sixteen healthy, non-obese volunteers and monitored their habitual sleep patterns via actigraphy for two weeks. Perhaps unsurprisingly, they were for the most part chronically sleep deprived, getting on average around 6.3 hours of sleep per night. Then, the researchers had the subjects increase their time in bed by one hour, which resulted in an average increase in sleep time of 49 minutes on weekdays and no significant difference on weekends. After 40 days of increased sleep time, participants showed lower levels of fasting insulin, as well as improvements in markers of insulin sensitivity. Notably, larger increases in sleep duration were linked to greater improvements in insulin sensitivity. How big of a difference can this make? Well, another study that looked at healthy men who routinely get short sleep on weekdays found that just three nights of sleep extension (10 hours per night) improved insulin sensitivity by 45%!
⚕️ Sleep extension lowers blood pressure.
Researchers recruited 18 men who were both overweight/obese and short sleepers at baseline. They were randomly assigned to either a program of sleep extension based on cognitive-behavioral principles or to a control group, and were followed for six weeks. Various blood markers, as well as blood pressure, were monitored over the course of the study. By the end of the program, the sleep extension group had managed to get 79 minutes of more sleep per night. They also showed improvements in metabolic health, as both fasting insulin and insulin resistance (measured by HOMA-IR) decreased significantly. Perhaps most impressively, their blood pressure dropped dramatically, with reductions in systolic (-11.09 mm Hg) and diastolic (-12.16 mm Hg) blood pressure, a degree comparable to the level seen from antihypertensive drugs. You might think that these kinds of huge improvements would be limited to people who are starting at high cardiovascular risk, like these subjects, but even healthy people can see some similar benefits. Another study that tested a shorter and less intensive sleep extension protocol in healthy young undergraduate students showed a 7.0 mm Hg reduction in systolic blood pressure.
🏋🏿 Sleep extension boosts athletic performance.
This is kind of an old study but it’s a good one. Researchers recruited eleven members of Stanford’s men’s basketball team, and monitored their baseline habitual sleep-wake schedule for a few weeks. Then, they had the players get as much sleep at night as they possibly could, with a minimum goal of ten hours in bed every night. After six weeks, the men had managed to increase their nightly sleep by an average of 110 more minutes. Following sleep extension, the subjects showed significant improvements in free throw accuracy (+9%) and 3-point field goal accuracy (+9.2%), and they also demonstrated faster sprint times (going from 16.2 sec to 15.5 sec). This was accompanied by better reaction time, greater vigor and subjective well-being, and decreased fatigue. A number of studies have since shown benefits for sleep extension in a wide range of athletic endeavors, including major league baseball and endurance sports.
Random Trivia & Weird News
Geese are able to sleep while flying.
Canada geese and other migratory birds have been known to fly a mind-boggling 1500 miles in the space of 24 hours. Part of how they are able to manage this, without suffering a serious toll from sleep deprivation, is through a behavior known as unihemispheric slow-wave sleep. In this process, one side of the brain can rest while the other side remains awake - and one eye even stays open looking for potential threats!
They sometimes do this while swimming as well, so if you ever see a goose on the water with one eye open, they are probably engaging in this half-sleep state. (I have to admit I am kind of jealous of this ability - think how much more you could get done if you were able to literally sleep while doing chores and other stuff)
Podcasts We Loved This Week
- Spencer Nadolsky & Karl Nadolsky: Do carbs cause obesity? Via Docs Who Lift Podcast.
- Colleen Evans: The brief and wondrous lives of cicadas. Via Science Friday.
Products We Are Enjoying
NatureMade Back to Sleep Fast-Dissolve Tablet
From a behavioral standpoint, the major thing that distinguishes sleep from other pillars of health (like nutrition and physical activity) is that it is not fully under our conscious control. Meaning, falling asleep and staying asleep isn’t necessarily like going for a walk or making a kale salad - it can be elusive despite your best efforts. That’s where supplements like this come in. Sometimes, I randomly wake up in the middle of the night and absolutely cannot go back to sleep, no matter what I do. It’s not an uncommon problem - you’ve probably experienced it yourself - but it is super frustrating. For this specific issue, I have found this supplement to be pretty helpful. It combines a low dose of melatonin with L-theanine, so you can get back to sleep without being too drowsy the next morning. Also, they dissolve in your mouth, so it absorbs fast and so you can just take it at your bedside without needing to get up and get water. Very convenient!
humanOS Catalog Feature of the Week
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