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January 29 - April 23, 2025
Should you tabulate millions of daily hospital records, as researchers have done, you discover that this seemingly trivial sleep reduction comes with a frightening spike in heart attacks the following day.
Excessively high levels of blood sugar, or glucose, over weeks or years inflicts a surprising harm to the tissues and organs of your body, worsens your health, and shortens your life span.
If the cells of your body stop responding to insulin, however, they cannot efficiently absorb glucose from the blood.
Independent of one another, the research groups found far higher rates of type 2 diabetes among individuals that reported sleeping less than six hours a night routinely.
Powerful as these studies are, though, they do not inform the direction of causality.
By the end of that week, these (formerly healthy) participants were 40 percent less effective at absorbing a standard dose of glucose, compared to when they were fully rested.
How does a lack of sleep hijack the body’s effective control of blood sugar?
In
Multiple forces conspire to expand your waistline. The first concerns two hormones controlling appetite: leptin and ghrelin.fn2 Leptin signals a sense of feeling full.
Ghrelin, in contrast, triggers a strong sensation of hunger.
At fault were the two characters, leptin and ghrelin. Inadequate sleep decreased concentrations of the satiety-signaling hormone leptin and increased levels of the hunger-instigating hormone ghrelin.
Does your waistline really swell as a consequence of that rise in appetite? With another landmark study, Van Cauter proved this to be the case.
Of relevance to this behavior is a recent discovery that sleep loss increases levels of circulating endocannabinoids, which, as you may have guessed from the name, are chemicals produced by the body that are very similar to the drug cannabis. Like marijuana use, these chemicals stimulate appetite and increase your desire to snack, otherwise known as having the munchies.
Some argue that we eat more when we are sleep-deprived because we burn extra calories when we stay awake. Sadly, this is not true.
Weight gain caused by short sleep is not just a matter of eating more, but also a change in what you binge eat.
we discovered that supervisory regions in the prefrontal cortex required for thoughtful judgments and controlled decisions had been silenced in their activity by a lack of sleep.
High-calorie foods became significantly more desirable in the eyes of the participants when sleep-deprived.
We found that a full night of sleep repairs the communication pathway between deep-brain areas that unleash hedonic desires and higher-order brain regions whose job it is to rein in these cravings.
South of the brain, we are also discovering that plentiful sleep makes your gut happier.
When you are not getting enough sleep, the body becomes especially stingy about giving up fat. Instead, muscle mass is depleted while fat is retained.
The size of the hormonal blunting effect is so large that it effectively “ages” a man by ten to fifteen years in terms of testosterone virility.
Males with low testosterone often feel tired and fatigued throughout the day. They find it difficult to concentrate on work tasks, as testosterone has a sharpening effect on the brain’s ability to focus.
Add to this the fact that testosterone maintains bone density, and plays a causal role in building muscle mass and therefore strength,
Moreover, the women working erratic hours were 80 percent more likely to suffer from issues of sub-fertility that reduced the ability to get pregnant.
The faces pictured after one night of short sleep were rated as looking more fatigued, less healthy, and significantly less attractive, compared with the appealing image of that same individual after they had slept a full eight hours.
An intimate and bidirectional association exists between your sleep and your immune system.
Sleep fights against infection and sickness by deploying all manner of weaponry within your immune arsenal, cladding you with protection. When you do fall ill, the immune system actively stimulates the sleep system, demanding more bed rest to help reinforce the war effort.
There was a clear, linear relationship with infection rate. The less sleep an individual was getting in the week before facing the active common cold virus, the more likely it was that they would be infected and catch a cold.
However, that flu shot is only effective if your body actually reacts to it by generating antibodies.
As with the effects of sleep deprivation on memory, once you miss out on the benefit of sleep in the moment—here, regarding an immune response to this season’s flu—you cannot regain the benefit simply by trying to catch up on lost sleep.
One such foreign entity that natural killer cells will target are malignant (cancerous) tumor cells.
Examining healthy young men in a careful study that controlled for spurious factors, such as physical activity, Irwin demonstrated that a single night of four hours of sleep—such as going to bed at three a.m. and waking up at seven a.m.—swept away 70 percent of the natural killer cells circulating in the immune system, relative to a full eight-hour night of sleep.
Cancers are known to use the inflammation response to their advantage.
Inflammatory factors associated with sleep deprivation may also be used to help physically shear some of the tumor from its local moorings, allowing the cancer to up-anchor and spread to other territories of the body.
Modern medicine is increasingly adept in its treatment of cancer when it stays put, but when cancer metastasizes—as was encouraged by the state of sleep disruption—medical intervention often becomes challenging, and death rates escalate.
After one week of subtly reduced sleep, the activity of a hefty 711 genes was distorted, relative to the genetic activity profile of these very same individuals when they were obtaining an eight and a half-hour sleep opportunity a night for a week.
The genes that were increased included those linked to chronic inflammation, cellular stress, and various factors that cause cardiovascular disease. Among those turned down were genes that help maintain stable metabolism and optimal immune responses.
If the telomeres at the end of your chromosomes become damaged, your DNA spirals become exposed and your now vulnerable genetic code cannot operate properly,
Short sleep and poor-quality sleep are both associated with greater damage to the capstone telomeres of an individual.
But the particular nature of the telomere damage caused by short sleeping is now becoming clear. It appears to mimic that seen in aging or advanced decrepitude. That is, two individuals of the same chronological age would not appear to be of the same biological age on the basis of their telomere health if one was routinely sleeping five hours a night while the other was sleeping seven hours a night.
Part 3 HOW AND WHY WE DREAM
Chapter 9 Routinely Psychotic
As you are falling asleep or exiting sleep, the dream-like experiences you have tend to be visually or movement based. But dreams as most of us think of them—those hallucinogenic, motoric, emotional, and bizarre experiences with a rich narrative—come from REM sleep, and many sleep researchers limit their definition of true dreaming to that which occurs in REM sleep.
During dreamless, deep NREM sleep, overall metabolic activity shows a modest decrease relative to that measured from an individual while they are resting but awake. However, something very different happens as the individual transitions into REM sleep and begins to dream. Numerous parts of the brain “light up” on the MRI scan as REM sleep takes hold, indicating a sharp increase in underlying activity.
Indeed, these emotional regions of the brain are up to 30 percent more active in REM sleep compared to when we are awake!
What came as a surprise, however, was a pronounced deactivation of other brain regions—specifically, circumscribed regions of the far left and right sides of the prefrontal cortex.
And it is this CEO region of your brain, which otherwise maintains your cognitive capacity for ordered, logical thought, that is temporarily ousted each time you enter into the dreaming state of REM sleep.
REM sleep can therefore be considered as a state characterized by strong activation in visual, motor, emotional, and autobiographical memory regions of the brain, yet a relative deactivation in regions that control rational thought.
But even without that dream report, we should be able to read the brain scans and accurately predict the nature of that person’s dream before they report it to us.
We have conducted just such an experiment, and the findings were so: we could predict with confidence the form of someone’s dream—would
