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The myth of the eight-hour sleep →

For the past several months, I've had trouble sleeping the entire way through the night. I fall asleep easily and sleep well until sometime between 2–4am. Then I wake up and can't fall back to sleep until about 90 minutes later. I've been thinking there's something wrong with me. There's not. I'm just reverting to medieval sleep patterns.

In 2001, historian Roger Ekirch of Virginia Tech published a seminal paper, drawn from 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct chunks.

His book At Day's Close: Night in Times Past, published four years later, unearths more than 500 references to a segmented sleeping pattern - in diaries, court records, medical books and literature, from Homer's Odyssey to an anthropological account of modern tribes in Nigeria.

Much like the experience of Wehr's subjects, these references describe a first sleep which began about two hours after dusk, followed by waking period of one or two hours and then a second sleep.

"It's not just the number of references - it is the way they refer to it, as if it was common knowledge," Ekirch says.

During this waking period people were quite active. They often got up, went to the toilet or smoked tobacco and some even visited neighbours. Most people stayed in bed, read, wrote and often prayed. Countless prayer manuals from the late 15th Century offered special prayers for the hours in between sleeps.

And these hours weren't entirely solitary - people often chatted to bed-fellows or had sex.

A doctor's manual from 16th Century France even advised couples that the best time to conceive was not at the end of a long day's labour but "after the first sleep", when "they have more enjoyment" and "do it better".

​And this isn't just a difference between older humans and more modern humans.

In the early 1990s, psychiatrist Thomas Wehr conducted an experiment in which a group of people were plunged into darkness for 14 hours every day for a month.

It took some time for their sleep to regulate but by the fourth week the subjects had settled into a very distinct sleeping pattern. They slept first for four hours, then woke for one or two hours before falling into a second four-hour sleep.

My problem — waking up and being unable to fall back to sleep right away ​— even has a name: sleep maintenance insomnia.

Today, most people seem to have adapted quite well to the eight-hour sleep, but Ekirch believes many sleeping problems may have roots in the human body's natural preference for segmented sleep as well as the ubiquity of artificial light.

This could be the root of a condition called sleep maintenance insomnia, where people wake during the night and have trouble getting back to sleep, he suggests.

The condition first appears in literature at the end of the 19th Century, at the same time as accounts of segmented sleep disappear.

"For most of evolution we slept a certain way," says sleep psychologist Gregg Jacobs. "Waking up during the night is part of normal human physiology."

​Maybe I should try sleeping from 8pm–midnight, reading or working on a project from midnight–2am and then sleeping again from 2–6am. It might just be good scientific practice.

Exercise Is Not the Path to Strong Bones →

I've heard, from multiple sources, that weight training can increase bone density and strength. According to Gina Kolata, at The New York Times, that's not actually true.

The answer came a little more than a decade ago when scientists did rigorous studies, asking if weight bearing exercise increased bone density in adults. They used DEXA machines, which measure bone density by hitting bones with X-rays. Those studies failed to find anything more than a minuscule exercise effect — on the order of 1 percent or less, which is too small to be clinically significant. As expected, DEXA found bone loss in people who were bedridden and in astronauts. But there was no evidence that bone was gained when people walked or ran.

Scientists have continued to investigate as tests for bone density grow ever more sensitive. More recently, using new and very expensive machines that scan bone and are able to show its structure at a microscopic scale, they reported a tiny exercise effect in one part of the bone’s architecture known as the trabecula, little branches inside bone that link to each other. The cortical shell — the outer layer of bone — also seems to be slightly thicker with weight bearing exercise. But these are minute changes, noted Dr. Clifford Rosen, a bone researcher at the Maine Medical Research Institute. There is no evidence that they make bone stronger or protect it from osteoporosis, he said.

Walking to Better Health

You may have heard that you should walk at least 10,000 steps per day, for your health. How good is that advice? The software developers at cardiogram have developed an app that tracks your heart rate, using your Apple Watch. They decided to combine the data from the Apple Watch's heart beat sensor with the data from the iPhone's step counter, to see how walking distance affects your resting heart rate.

I'm not sure how scientifically rigorous these results are, but they did come up with some interesting correlations.

Graph of step count versus heart rate

In cardiovascular terms, the drop in heart rate from 1000 steps/day to 2000 steps/day is significant: a full 3 bpm decrease. And as step count increases, resting heart rate steadily drops—until you reach about 5000 steps per day. After that—6000, 7000, even up to 10,000 steps—the curve flattens.

Graph of exercise intensity versus heart rate

Even if you get 10,000 steps per day, if your heart rate doesn’t go over 130 bpm, there’s not much impact on your resting heart rate. In contrast, even 4000 steps / day of high intensity exercise delivers a benefit: about a 4 bpm absolute drop in resting bpm, which doubles to 8 bpm at 10,000 steps / day.

Graph of minutes of high intensity exercise versus heart rate

Even 45 minutes per week of high intensity activity (heart rate >= 150bpm) placed participants in the lowest tier of resting heart rate.

I like this kind of analysis because it's actionable. I've been making some, small, effort to walk each day. I have a goal of 5,000 steps per day. But I've been skeptical of whether or not it actually matters, if it's just a few steps here and there. According to these numbers, it doesn't. I'm just fooling myself.

I can use these numbers to make a new goal. I want to start taking high-intensity walks 2-3 times a week. I've already been monitoring my heart rate. It stays around 90 beats per minute, most days. My initial goal is to lower that to 80 bpm. If that happens, I'll set a new goal.

The Fat Trap →

I think, as a society, we need to stop looking at weight as a moral issue and look at it more as a medical issue. Some people don't gain weight, no matter what they do. Others can't lose weight (and keep it off) no matter what they do. It appears that biology matters far more than mere willpower.

While researchers have known for decades that the body undergoes various metabolic and hormonal changes while it’s losing weight, the Australian team detected something new. A full year after significant weight loss, these men and women remained in what could be described as a biologically altered state. Their still-plump bodies were acting as if they were starving and were working overtime to regain the pounds they lost. For instance, a gastric hormone called ghrelin, often dubbed the “hunger hormone,” was about 20 percent higher than at the start of the study. Another hormone associated with suppressing hunger, peptide YY, was also abnormally low. Levels of leptin, a hormone that suppresses hunger and increases metabolism, also remained lower than expected. A cocktail of other hormones associated with hunger and metabolism all remained significantly changed compared to pre-dieting levels. It was almost as if weight loss had put their bodies into a unique metabolic state, a sort of post-dieting syndrome that set them apart from people who hadn’t tried to lose weight in the first place.

… Another way that the body seems to fight weight loss is by altering the way the brain responds to food. Rosenbaum and his colleague Joy Hirsch, a neuroscientist also at Columbia, used functional magnetic resonance imaging to track the brain patterns of people before and after weight loss while they looked at objects like grapes, Gummi Bears, chocolate, broccoli, cellphones and yo-yos. After weight loss, when the dieter looked at food, the scans showed a bigger response in the parts of the brain associated with reward and a lower response in the areas associated with control. This suggests that the body, in order to get back to its pre-diet weight, induces cravings by making the person feel more excited about food and giving him or her less willpower to resist a high-calorie treat.

This entry was tagged. Food Healthy Living

Who wants to live forever?

Do you want to live for a long time, in decent health? If the rate of innovation in medical science doesn’t slow down, you just may be able to.

If Aubrey de Grey's predictions are right, the first person who will live to see their 150th birthday has already been born. And the first person to live for 1,000 years could be less than 20 years younger.

A biomedical gerontologist and chief scientist of a foundation dedicated to longevity research, de Grey reckons that within his own lifetime doctors could have all the tools they need to "cure" aging -- banishing diseases that come with it and extending life indefinitely.

"I'd say we have a 50/50 chance of bringing aging under what I'd call a decisive level of medical control within the next 25 years or so," de Grey said in an interview before delivering a lecture at Britain's Royal Institution academy of science.

"And what I mean by decisive is the same sort of medical control that we have over most infectious diseases today."

De Grey sees a time when people will go to their doctors for regular "maintenance," which by then will include gene therapies, stem cell therapies, immune stimulation and a range of other advanced medical techniques to keep them in good shape.

A Standing Desk? →

I’ve been considering switching to a standing desk for about a year now. This article from Art of Manliness gives a good overview for why and how.

5 Reasons Why:

  1. To Avoid an Early Grave
  2. To Lose Weight
  3. To Save Your Back
  4. To Increase Your Focus
  5. To Gain a Satisfying Tiredness