Tag Archives: sleep

Together, Unconscious: We All Sleep

One constant that connects us all in some way is that–at the end of our day–we lie down and slowly slip into a state of reduced or absent consciousness and become at the mercy of our fellow man. Every day we fall asleep: we have done so for millions of years and will continue to do so.

This humbling thought was inspired by David Cain’s short disquisition on how the act of sleeping is something that unites us together, all around the world. David’s post didn’t quite take the route I was expecting after reading the (wonderful) excerpt below1, but is still definitely worth a read.

It’s an interesting quirk of Mother Nature — that she insists on taking us down to the ground like that, every day, no matter who we are. For all of us, the act of leaving consciousness is the same, it’s just our settings and situations — which bookend that unconsciousness — where we differ.

via Link Banana

1 I was expecting the post to concentrate on the first sentence (leaving consciousness), rather than the second sentence (sleep as a connector).

Illness Susceptibility and Sleep Quality

I’ve been ill for a few weeks and I was fairly sure (in my amateur opinion) that it was related to a significant lack of sleep over the last couple of months. Upon returning to full health I decided to do some quick research on my favourite topic: sleep.

In one recent study looking at sleep habits and resulting susceptibility to the common cold it was found that both sleep length and sleep quality were “important predictors of immunity and, in turn, susceptibility”.

Specifically, “those who slept an average of fewer than seven hours a night […] were three times as likely to get sick as those who averaged at least eight hours”. Furthermore, people who had 92% sleep efficiency were five and a half times more susceptible compared to those with 98% sleep efficiency (defined as the percentage of time in bed actually asleep).

The New York Times article that led me to this study continues:

Sleep and immunity, it seems, are tightly linked. Studies have found that mammals that require the most sleep also produce greater levels of disease-fighting white blood cells — but not red blood cells, even though both are produced in bone marrow and stem from the same precursor. And researchers at the Max Planck Institute for Evolutionary Anthropology have shown that species that sleep more have greater resistance against pathogens.

The more you know… (the more you sleep?)

Update: I’ve briefly mentioned this study on Lone Gunman before, but I think the cognitive impact was the most interesting titbit in that Jonah Lehrer article.

Gradual Sleep Deprivation, Obesity and Cognitive Impairment

By getting less than our required amount of sleep over an extended period of time (two weeks, for example) we are increasing our risk of obesity and impairing our cognitive abilities without even being aware of it.

That’s the conclusion from a short article summarising the surprising effects of gradual sleep deprivation:

Researchers […] restricted volunteers to less than six hours in bed per night for two weeks. The volunteers perceived only a small increase in sleepiness and thought they were functioning relatively normally. However, formal testing showed that their cognitive abilities and reaction times progressively declined [until] they were as impaired as subjects who had been awake continuously for 48 hours.

Moreover, […] too little sleep changes the body’s secretion of some hormones. The changes promote appetite, reduce the sensation of feeling full after a meal, and alter the body’s response to sugar intake—changes that can promote weight gain and increase the risk of developing diabetes. […]

A recent review […] of the large studies that followed people over time agreed that short sleep duration was associated with future weight gain. […] For example, [one study] showed an inverse correlation between sleep duration and obesity in high-school-age students. The shorter the sleep, the higher the likelihood of being overweight, with those getting six to seven hours of sleep more than two and a half times as likely to be overweight as those getting more than eight hours. […]

The good news is that these effects can be reversed by getting an adequate amount of sleep. […] Allowing the study subjects to sleep 10 hours for two consecutive nights returned the hormones to normal levels and lowered hunger and appetite ratings by almost 25 percent.

via @finiteattention

Routine, Sleep and Premature Death

Sleeping for less that six hours a night is correlated strongly with an increased risk of premature death over a 25-year period (a 12% increase in the likelihood of your premature death, to be exact).

That’s the conclusion from an extensive report (studying 1.5 million people) convincingly showing the link between quality sleep and one’s health/well-being.

The study looked at the relationship between sleep and mortality by reviewing earlier studies from the UK, US and European and East Asian countries.

Premature death from all causes was linked to getting either too little or too much sleep outside of the “ideal” six to eight hours per night.

But while a lack of sleep may be a direct cause of ill health, ultimately leading to an earlier death, too much sleep may merely be a marker of ill health already.

That last bit’s important (correlation not causation), with one researcher calling sleep the “litmus paper to physical and mental health”.

Another report in the same journal (Sleep) demonstrated the importance of a stable daily routine in getting a good night’s sleep (although thus far it has only been shown in the elderly):

Increased stability in daily routine […] predicted shorter sleep latency, higher sleep efficiency and improved sleep quality. […] Maintenance of daily routines is associated with a reduced rate of insomnia in the elderly.

So… stop your happy-go-lucky, spur-of-the-moment, devil-may-care lifestyle; live to a timetable; live longer?

Sleep for Creativity

Dreams are not “meaningless narratives” but are “layered with significance and substance”, laments insomniac Jonah Lehrer as he considers the importance of dreaming for creativity:

A group of students was given a tedious task that involved transforming a long list of number strings into a new set of number strings. This required the subjects to apply a painstaking set of algorithms. However, […] there was an elegant shortcut, which could only be uncovered if the subjects saw the subtle links between the different number sets. When left to their own devices, less than 25 percent of people found the shortcut, even when given several hours to mull over the task. However, when [the researcher, Jan Born,] allowed people to sleep between experimental trials, they suddenly became much more clever: 59 percent of all participants were able to find the shortcut. Born argues that deep sleep and dreaming “set the stage for the emergence of insight” by allowing us to mentally represent old ideas in new ways.

So that’s another good reason to sleep well.

Before looking at how sleep is “an essential component of creativity”, Lehrer also describes this fascinating study: a selection of rodents spent their day running around a circular track, having their brain activity monitored. Once the animals fell asleep, the researchers noted that the brain activity displayed was identical to that displayed while they were actually running around the track (i.e. they were dreaming about running). On further examination, the researchers then discovered that they could also predict precisely where on the track the rodents were at any given point in their dream.