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October 20 - November 15, 2024
Dreaming provides a unique suite of benefits to all species fortunate enough to experience it, humans included. Among these gifts are a consoling neurochemical bath that mollifies painful memories and a virtual reality space in which the brain melds past and present knowledge, inspiring creativity.
The physical and mental impairments caused by one night of bad sleep dwarf those caused by an equivalent absence of food or exercise.
sleep is the single most effective thing we can do to reset our brain and body health each day—Mother
Melatonin simply provides the official instruction to commence the event of sleep, but does not participate in the sleep race itself.
For every day you are in a different time zone, your suprachiasmatic nucleus can only readjust by about one hour.
Caffeine works by successfully battling with adenosine for the privilege of latching on to adenosine welcome sites—or receptors—in the brain.
Caffeine has an average half-life of five to seven hours.
When it comes to information processing, think of the wake state principally as reception (experiencing and constantly learning the world around you), NREM sleep as reflection (storing and strengthening those raw ingredients of new facts and skills), and REM sleep as integration (interconnecting these raw ingredients with each other, with all past experiences, and, in doing so, building an ever more accurate model of how the world works, including innovative insights and problem-solving abilities).
hours. Total amount of time is one of the most conspicuous differences in how organisms sleep.
can never “sleep back” that which we have previously lost is one of the most important take-homes of this book,
Throughout developed nations, most adults currently sleep in a monophasic pattern—that is, we try to take a long, single bout of slumber at night, the average duration of which is now less than seven hours. Visit cultures that are untouched by electricity and you often see something rather different. Hunter-gatherer tribes, such as the Gabra in northern Kenya or the San people in the Kalahari Desert, whose way of life has changed little over the past thousands of years, sleep in a biphasic pattern. Both these groups take a similarly longer sleep period at night (seven to eight hours of time in
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The practice of biphasic sleep is not cultural in origin, however. It is deeply biological. All humans, irrespective of culture or geographical location, have a genetically hardwired dip in alertness that occurs in the midafternoon hours.
Alcohol is one of the most powerful suppressors of REM sleep that we know of.
the brain areas that generate sleep are molded in place well before birth, the master twenty-four-hour clock that controls the circadian rhythm—the suprachiasmatic nucleus—takes considerable time to develop. Not until age three or four months will a newborn show modest signs of being governed by a daily rhythm.
By the one-year milestone of development, the suprachiasmatic nucleus clock of an infant has gripped the steering reins of the circadian rhythm.
the proportion of REM sleep decreases in early childhood while the proportion of NREM sleep actually increases, even though total sleep time decreases.
why rationality is one of the last things to flourish in teenagers, as it is the last brain territory to receive sleep’s maturational treatment.
Those individuals who developed schizophrenia had an abnormal pattern of brain maturation that was associated with synaptic pruning, especially in the frontal lobe regions where rational, logical thoughts are controlled—the inability to do so being a major symptom of schizophrenia.
As parents, we are often too focused on what sleep is taking away from our teenagers, without stopping to think about what it may be adding.
That older adults simply need less sleep is a myth. Older adults appear to need just as much sleep as they do in midlife, but are simply less able to generate that (still necessary) sleep.
As you enter your fourth decade of life, there is a palpable reduction in the electrical quantity and quality of that deep NREM sleep.
But far more of our age-related physical and mental health ailments are related to sleep impairment than either we, or many doctors, truly realize or treat seriously.
The second hallmark of altered sleep as we age, and one that older adults are more conscious of, is fragmentation. The older we get, the more frequently we wake up throughout the night. There are many causes, including interacting medications and diseases, but chief among them is a weakened bladder.
Any individual, no matter what age, will exhibit physical ailments, mental health instability, reduced alertness, and impaired memory if their sleep is chronically disrupted.
older adults who want to shift their bedtimes to a later hour should get bright-light exposure in the late-afternoon hours.
First, wear sunglasses during morning exercise outdoors. This will reduce the influence of morning light being sent to your suprachiasmatic clock that would otherwise keep you on an early-to-rise schedule.
Second, go back outside in the late afternoon for sunlight exposure, but this time do not wear sunglasses.
Plentiful later-afternoon daylight will help delay the evening release of melatonin, helping push the ti...
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the areas of the brain that suffer the most dramatic deterioration with aging are, unfortunately, the very same deep-sleep-generating regions—the middle-frontal regions seated above the bridge of the nose.
saddening confirmation of my theory: the parts of our brain that ignite healthy deep sleep at night are the very same areas that degenerate, or atrophy, earliest and most severely as we age.
Poor memory and poor sleep in old age are therefore not coincidental, but rather significantly interrelated.
Sleep six hours or less and you are shortchanging the brain of a learning restoration benefit that is normally performed by sleep spindles.
memory retention benefit of between 20 and 40 percent being offered by sleep, compared to the same amount of time awake.
For fact-based, textbook-like memory, the result was clear. It was early-night sleep, rich in deep NREM, that won out in terms of providing superior memory retention savings relative to late-night, REM-rich sleep.
the more deep NREM sleep, the more information an individual remembered the next day.
Even daytime naps as short as twenty minutes can offer a memory consolidation advantage, so long as they contain enough NREM sleep.V
SLEEP TO FORGET?
sleep does not offer a general, nonspecific (and hence verbose) preservation of all the information you learn during the day. Instead, sleep is able to offer a far more discerning hand in memory improvement: one that preferentially picks and chooses what information is, and is not, ultimately strengthened.
Muscle memory is, in fact, brain memory. Training and strengthening muscles can help you better execute a skilled memory routine. But the routine itself—the memory program—resides firmly and exclusively within the brain.
In other words, your brain will continue to improve skill memories in the absence of any further practice.
Practice does not make perfect. It is practice, followed by a night of sleep, that leads to perfection.
The increases in speed and accuracy, underpinned by efficient automaticity, were directly related to the amount of stage 2 NREM, especially in the last two hours of an eight-hour night of sleep
daytime naps that contain sufficient numbers of sleep spindles also offer significant motor skill memory improvement, together with a restoring benefit on perceived energy and reduced muscle fatigue.
the most dramatic time of skilled motor learning in any human’s life occurs in the first years after birth, as we start to stand and walk. It is of little surprise that we see a spike in stage 2 NREM sleep, including sleep spindles, right around the infant’s time of transition from crawling to walking.
A final benefit of sleep for memory is arguably the most remarkable of all: creativity.
No facet of the human body is spared the crippling, noxious harm of sleep loss.
One brain function that buckles under even the smallest dose of sleep deprivation is concentration.
After four hours of sleep for six nights, participants’ performance was just as bad as those who had not slept for twenty-four hours straight—that is, a 400 percent increase in the number of microsleeps.
Ten days of six hours of sleep a night was all it took to become as impaired in performance as going without sleep for twenty-four hours straight. And like the total sleep deprivation group, the accruing performance impairment in the four-hour and six-hour sleep groups showed no signs of leveling out.
With chronic sleep restriction over months or years, an individual will actually acclimate to their impaired performance, lower alertness, and reduced energy levels. That low-level exhaustion becomes their accepted norm, or baseline.
