Stand Up While You Read This! - Olivia Judson - NYTimes.com
...It doesn’t matter if you go running every morning, or you’re a regular at the gym. If you spend most of the rest of the day sitting ... you are putting yourself at increased risk of obesity, diabetes, heart disease, a variety of cancers and an early death. In other words, irrespective of whether you exercise vigorously, sitting for long periods is bad for you...... Several strands of evidence suggest that there’s a “physiology of inactivity”: that when you spend long periods sitting, your body actually does things that are bad for you....
... consider lipoprotein lipase. This is a molecule that plays a central role in how the body processes fats; it’s produced by many tissues, including muscles. Low levels of lipoprotein lipase are associated with a variety of health problems, including heart disease. Studies in rats show that leg muscles only produce this molecule when they are actively being flexed (for example, when the animal is standing up and ambling about). The implication is that when you sit, a crucial part of your metabolism slows down.
How siestas help memory: Sleepy heads | The Economist
... It has already been established that those who siesta are less likely to die of heart disease. Now, Matthew Walker and his colleagues at the University of California, Berkeley, have found that they probably have better memory, too. A post-prandial snooze, Dr Walker has discovered, sets the brain up for learning....
... The ideal nap, then, follows a cycle of between 90 and 100 minutes. The first 30 minutes is a light sleep that helps improve motor performance. Then comes 30 minutes of stage 2 sleep, which refreshes the hippocampus. After this, between 60 and 90 minutes into the nap, comes rapid-eye-movement, or REM, sleep, during which dreaming happens. This, research suggests, is the time when the brain makes connections between the new memories that have just been “downloaded” from the hippocampus and those that already exist—thus making new experiences relevant in a wider context.Wireless headsets mean we can do calls easily while standing, pacing, even doing some light weight lifting -- or perhaps while going for a walk (though not with an AT&T iPhone - the connection will drop). Siestas are tougher. There's much to be said for working remotely ...
The benefits to memory of a nap, says Dr Walker, are so great that they can equal an entire night’s sleep. He warns, however, that napping must not be done too late in the day or it will interfere with night-time sleep. Moreover, not everyone awakens refreshed from a siesta.
The grogginess that results from an unrefreshing siesta is termed “sleep inertia”. This happens when the brain is woken from a deep sleep with its cells still firing at a slow rhythm and its temperature and blood flow decreased. Sara Mednick, from the University of California, San Diego, suggests that non-habitual nappers suffer from this more often than those who siesta regularly. It may be that those who have a tendency to wake up groggy are choosing not to siesta in the first place. Perhaps, though, as in so many things, it is practice that makes perfect.
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