I like one of Elena Ferrante’s conclusions as she approaches old age: “Unlike stories, real life, when it has passed, inclines towards obscurity not clarity.”
Words flow from her like ink from a damaged pen, and none are superfluous or fatuous.
The Neapolitan novels.
As Dinin put it, “Compelling.”
Saturday, December 29, 2018
My 261st consecutive posting, committed to 5,000.
Time is 12.01am.
On Saturday, Boston’s temperature will reach a high of 50* with some wind resulting in a feels-like temperature of 42.
The low will plummet to 26*.
Dinner is steak.
Question of the Day:
Yesterday we posted a piece on naps.
Can we post something on sleep?
Love your notes.
Contact me @ firstname.lastname@example.org
On the posting re: naps
From Marc Olivere
This morning when I sat down to write, I started with a reading of your blog. Now I’m ready to take a nap.
It must be the coffee.
Web Meister Responds: Cute. Very cute.
Answer to Today’s Question:
Sleep is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings.
It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than coma or disorders of consciousness, sleep displaying very different and active brain patterns.
Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body.
During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; these are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems.
The internal circadian clock promotes sleep daily at night.
The diverse purposes and mechanisms of sleep are the subject of substantial ongoing research.
Sleep is a highly conserved behavior across animal evolution.
Humans may suffer from various sleep disorders, including dyssomnias such as insomnia, hypersomnia, narcolepsy, and sleep apnea; parasomnias such as sleepwalking and REM behavior disorder; bruxism; and circadian rhythm sleep disorders.
The advent of artificial light has substantially altered sleep timing in industrialized countries.
The most pronounced physiological changes in sleep occur in the brain.
The brain uses significantly less energy during sleep than it does when awake, especially during non-REM sleep.
In areas with reduced activity, the brain restores its supply of adenosine triphosphate (ATP), the molecule used for short-term storage and transport of energy.
In quiet waking, the brain is responsible for 20% of the body's energy use, thus this reduction has a noticeable effect on overall energy consumption.
Sleep increases the sensory threshold. In other words, sleeping persons perceive fewer stimuli, but can generally still respond to loud noises and other salient sensory events.
During slow-wave sleep, humans secrete bursts of growth hormone. All sleep, even during the day, is associated with secretion of prolactin.
Key physiological methods for monitoring and measuring changes during sleep include electroencephalography (EEG) of brain waves, electrooculography (EOG) of eye movements, and electromyography (EMG) of skeletal muscle activity. Simultaneous collection of these measurements is called polysomnography, and can be performed in a specialized sleep laboratory.
Sleep researchers also use simplified electrocardiography (EKG) for cardiac activity and actigraphy for motor movements.
Non-REM and REM sleep
Sleep is divided into two broad types: non-rapid eye movement (non-REM or NREM) sleep and rapid eye movement (REM) sleep.
Non-REM and REM sleep are so different that physiologists identify them as distinct behavioral states.
Non-REM sleep occurs first and after a transitional period is called slow-wave sleep or deep sleep.
During this phase, body temperature and heart rate fall, and the brain uses less energy.
REM sleep, also known as paradoxical sleep, represents a smaller portion of total sleep time.
It is the main occasion for dreams (or nightmares), and is associated with desynchronized and fast brain waves, eye movements, loss of muscle tone, and suspension of homeostasis.
The sleep cycle of alternate NREM and REM sleep takes an average of 90 minutes, occurring 4–6 times in a good night's sleep.
The American Academy of Sleep Medicine (AASM) divides NREM into three stages: N1, N2, and N3, the last of which is also called delta sleep or slow-wave sleep.
The whole period normally proceeds in the order: N1 → N2 → N3 → N2 → REM.
REM sleep occurs as a person returns to stage 2 or 1 from a deep sleep.
There is a greater amount of deep sleep (stage N3) earlier in the night, while the proportion of REM sleep increases in the two cycles just before natural awakening.
Sleep timing depends greatly on hormonal signals from the circadian clock, or Process C, a complex neurochemical system which uses signals from an organism's environment to recreate an internal day–night rhythm.
Process C counteracts the homeostatic drive for sleep during the day (in diurnal animals) and augments it at night.
The suprachiasmatic nucleus (SCN), a brain area directly above the optic chiasm, is presently considered the most important nexus for this process; however, secondary clock systems have been found throughout the body.
An organism whose circadian clock exhibits a regular rhythm corresponding to outside signals is said to be entrained; an entrained rhythm persists even if the outside signals suddenly disappear.
If an entrained human is isolated in a bunker with constant light or darkness, he or she will continue to experience rhythmic increases and decreases of body temperature and melatonin, on a period which slightly exceeds 24 hours.
Scientists refer to such conditions as free-running of the circadian rhythm.
Under natural conditions, light signals regularly adjust this period downward, so that it corresponds better with the exact 24 hours of an Earth day.
The clock exerts constant influence on the body, effecting sinusoidal oscillation of body temperature between roughly 36.2 °C and 37.2 °C.
The suprachiasmatic nucleus itself shows conspicuous oscillation activity, which intensifies during subjective day (i.e., the part of the rhythm corresponding with daytime, whether accurately or not) and drops to almost nothing during subjective night.
The circadian pacemaker in the suprachiasmatic nucleus has a direct neural connection to the pineal gland, which releases the hormone melatonin at night.
Cortisol levels typically rise throughout the night, peak in the awakening hours, and diminish during the day.
Circadian prolactin secretion begins in the late afternoon, especially in women, and is subsequently augmented by sleep-induced secretion, to peak in the middle of the night.
Circadian rhythm exerts some influence on the nighttime secretion of growth hormone.
The circadian rhythm influences the ideal timing of a restorative sleep episode.
Sleepiness increases during the night.
REM sleep occurs more during body temperature minimum within the circadian cycle, whereas slow-wave sleep can occur more independently of circadian time.
The internal circadian clock is profoundly influenced by changes in light, since these are its main clues about what time it is.
Exposure to even small amounts of light during the night can suppress melatonin secretion, and increase body temperature and wakefulness.
Short pulses of light, at the right moment in the circadian cycle, can significantly 'reset' the internal clock.
Blue light, in particular, exerts the strongest effect, leading to concerns that electronic media use before bed may interfere with sleep.
Modern humans often find themselves desynchronized from their internal circadian clock, due to the requirements of work (especially night shifts), long-distance travel, and the influence of universal indoor lighting.
Even if they have sleep debt, or feel sleepy, people can have difficulty staying asleep at the peak of their circadian cycle.
Conversely they can have difficulty waking up in the trough of the cycle.
A healthy young adult entrained to the sun will (during most of the year) fall asleep a few hours after sunset, experience body temperature minimum at 6AM, and wake up a few hours after sunrise.
Good morning on this Saturday, December 29
We admired Ferrante’s thought process and Marc brought a smile to our lips with his wit.
But mostly we talked about sleep, illustrating with lots of great pictures.
Che vuoi? Le pocketbook?
See you soon.