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Brain

Brain structure basics

Melatonin

Meditation

  • Why Meditate? | Change your Brain's Default Mode. See also: A Wandering Mind Is an Unhappy Mind (in PDF). or here (in html). Indeed,“stimulus-independent thought” or “mind wandering” appears to be the brain’s default mode of operation. ... Mind wandering occurred in 46.9% of the samples. ... Second, multilevel regression revealed that people were less happy when their minds were wandering than when they were not [slope (b) = –8.79, P < 0.001], and this was true during all activities, ncluding the least enjoyable. ... Although negative moods are known to cause mind wandering (13), time-lag analyses strongly suggested that mind wandering in our sample was generally the cause, and not merely the consequence, of unhappiness. ... Third, what people were thinking was a better
    predictor of their happiness than was what they were doing. ... In conclusion, a human mind is a wandering mind, and a wandering mind is an unhappy mind. The ability to think about what is not happening is a cognitive achievement that comes at an emotional cost.

Basics on sleep

  • Slow-Wave Sleep occurs more at the beginning, and is characterized by slow rhythms of electrical activity across large numbers of brain cells, occurring 1 to 4 times per second. It reflects the storing of the so-called "declarative" memories, that are the conscious record of our experiences and what we are aware of (e.g. what we had for breakfast). There is interaction with the hypocampus to turn these memories into long-term memories in the neocortex.
  • Rapid Eye Movement (REM) Sleep is thought to be important for emotional memories, memories involving fear or procedural memory such as how to ride a bike.
  • Synaptic Homeostasis Hypothesis. This suggests that during sleep there is a widespread weakening of connections or "synapses" throught the brain. Also referred to as "pruning."
  • Toxin cleanse. A recent study found sleep cleanses the brain of toxins that accumulate during waking hours, some of which are linked to neurodegenerative diseases. During sleep, the space between brain cells increases, allowing toxic proteins (i.e. metabolites) to be flushed out. There is a 60% increase in interstitial space. Better CSF (Cortical Surface Fluid) flow.
  • Declarative vs. Procedural Memory. Procedural memory involves physical actions like learning how to ride a bicycle.
  • Biphasic sleep (or diphasic, bimodal or bifurcated sleep) is the practice of sleeping during two periods over 24 hours. History suggest that this segmented sleep was the common form of sleeping prior to the industrial age. It was often referred to as the "first" and "second" sleep. See: The myth of the eight-hour sleep. In 2001, historian Roger Ekirch of Virginia Tech published a seminal paper, drawn from 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct chunks. ... In the early 1990s, psychiatrist Thomas Wehr conducted an experiment in which a group of people were plunged into darkness for 14 hours every day for a month. It took some time for their sleep to regulate but by the fourth week the subjects had settled into a very distinct sleeping pattern. They slept first for four hours, then woke for one or two hours before falling into a second four-hour sleep.
  • Alternative Sleep Schedule Overviews. Monophasic, segmented (biphasic), siesta (biphasic), triphasic, everyman, dual core, uberman, dymaxion, SPAMAYL.
  • In short photoperiods, human sleep is biphasic. When normal individuals were transferred from a conventional 16-h photoperiod to an experimental 10-h photo-period, their sleep episodes expanded and usually divided into two symmetrical bouts, several hours in duration, with a 1-3 h waking interval between them. Here is the full article: In short photoperiods, human sleep is biphasic. See also: Thomas Wehr (Wikipedia). Wehr placed a group of volunteers in an environment in which it was dark for 14 hours each day for a month. The subjects were able to sleep as much as they wanted during the experiment. The first night, the subjects slept an average of 11 hours a night. This was judged as probably repaying a chronic sleep debt. By the fourth week, the subjects slept an average of eight hours a night – but across two separate blocks, not unbroken. First, subjects tended to lie awake for one to two hours and then fall quickly asleep. ... After an average of three to five hours of sleep, the subjects would awaken and spend an hour or two in quiet wakefulness before a second three- to five-hour sleep period. It was thus suggested that such a biphasic pattern of sleep is the natural or pre-historic tendency for humans.
  • Prolactin hormone levels during sleep. See Prolactin. Prolactin follows diurnal and ovulatory cycles. Prolactin levels peak during REM sleep and in the early morning. Prolactin counterbalances dopamine.
  • Why Light Matters. Just as the ear provides hearing as well as the non-hearing function of balance, the eye provides both vision and temporal regulation. The visual system, cones in particular, have a peak sensitivity to green light. Ganglion cells, which aid with temporal regulation, have a peak sensitivity to blueish light. Blueish light produces two effects: It provides an alerting effect similar to coffee, and it regulates our body clock. ... Inside the home, a low circadian impact would be colors in the yellow-orange range. And, obviously, the blues would have high circadian impact.
  • Body clock. At 24.3 hours, the human clock is slightly longer than the 24 hour daily cycle. The proper light stimulus received in morning hours will reduce the 24.3 hour cycle while light exposure in the evening can advance the cycle. The former allows you to fall asleep earlier while the latter can postpone your bedtime, reducing sleep time, resulting in fatigue or a lack of alertness the following day, and potentially making you less productive.
  • Deep sleep (dynamics). Perhaps the most important part of deep sleep is the release of HGH. In children, it's what allows them to fully develop; in adults, it's how our body maintains and repairs itself. Also, muscles receive more blood supply. Declarative memory (learning of information) is processed (consolidated) during deep sleep; whereas, procedural memory is mainly processed (consolidated) during REM sleep. Most of deep sleep occurs in the first half of the night. Most of REM sleep occurs in the second half. References: What is Deep Sleep? (Stage, significance, and aging).
  • Sleep, performance and health in a 24/7 culture. Duration 1:21:47. Excellent video detailing sleep structure, etc.

Notes on sleep

  • Bible references. Psalm 119:62 (ESV) "At midnight I rise to praise you, because of your righteous rules.". Acts 16:25 (ESV) "About midnight Paul and Silas were praying and singing hymns to God, and the prisoners were listening to them."
  • Early Church. The Apostles observed the Jewish custom of praying at midnight, terce, sext, none (Acts 10:3, 9; 16:25; etc.). The Christian prayer of that time consisted of almost the same elements as the Jewish: recital or chanting of psalms, reading of the Old Testament, to which was soon added reading of the Gospels, Acts, and Epistles, and at times canticles composed or improvised by the assistants. Reference (Catholic Encyclopedia, "Divine Office")
  • Matthew Walker: "Why We Sleep: The New Science of Sleep and Dreams" | Talks at Google. Fewer car accidents, fewer heart attacks with more sleep, even just one hour extra of sleep.
  • Blue Free Light: What You Need To Know. Now, the problem is artificial light at night, because you’re getting blue light in the evening. Especially when you have LED lighting, all of these LEDs are stimulating the blue light sensors in your eyes when they shouldn’t, and that indicates to your body that it’s still daytime, when in fact it is night. Science has shown that exposure to blue light in the evenings delays the onset of our sleepiness, which ultimately messes up our circadian rhythm.
  • WHY Sleep is critical for the Body and Brain | Science of Sleep. Published 1/28/2017. Excellent overview of the current research in the benefits of sleep. 70% of the articles and books I've read on sleep will say something like "Sleep is one of the big mysteries of biology" at least once. While it is not 100% understood, there is a lot that is known about the impressive health, fitness and anti-aging effects of sleep. Sleep is particularly important for memory, mental flexibility, creativity and the development of novel insights. See part 2 here: HOW to get more quality sleep | (Science of Sleep Pt 2)
  • Bodybuilding for the brain: John Pelley at TEDxTexasTechUniversity. Published 2/19/2014. "Brain cells grow in size." They grow by branching more—i.e. increased dendrites. It appears that dendrites increase only during sleep. That is, the information is made permanent during deep sleep (i.e. SWS or Slow Wave Sleep). The speaker suggest that the memory must be attached to emotion in order for it to become permanent. Also see: New Study Provides Physical Evidence Of The Sleep-Learning Link.
  • We May Finally Know Why Sleep Improves Memory. Published 6/5/2014. Gan and his colleagues found that the sleep-deprived mice sprouted significantly fewer dendritic spines than those that were permitted to rest, and the rate of spine formation was correlated with the degree of task improvement. Growth was shown to be most dramatic during the slow-wave, non-REM stage of sleep. What's more, the benefits of sleep seem to carry on well after the mice woke up, with roughly 5% of new spines in the motor cortex developing in the 24 hours after the mice awoke. The mice that slept were also more likely to retain the spines they grew. In some circumstances, it seems sleep could in fact lead to the growth of new synapses. See original research here: Sleep promotes branch-specific formation of dendritic spines after learning.
  • The Role of Slow Wave Sleep in Memory Processing. Published 4/15/2009. Evidence now suggests that sleep is important in the processing of newly acquired information and for the long-term storage of memory. This has become known as “sleep-dependent memory processing.” Memories can be initially formed or “encoded” when the brain engages in an idea, image, thought, experience, or action, leading to the formation of a representation of this information in the brain. However, following encoding, this memory then appears to require “consolidation,” which refers to the process of memory stabilization over time, making it more resistant to interference or disruption. Memories can also be reconsolidated should they become destabilized, deteriorate, or require enhancement. Sleep has been implicated in all of these processes. ... An implication of the data presented above is that sleep, and SWS in particular, appears to be associated with an increase in episodic declarative memory consolidation. ... Overall, this evidence supports the role of SWS in memory processing and its importance before learning, to prepare the brain for initial memory encoding, and after learning, for the offline consolidation of new memories.
  • Intermittent Fasting - How it Affects Sleep. Published 1/13/2018. It's common to have sleep trouble with fasting, but intermittent fasting should actually improve sleep.
  • Dr. Satchin Panda on Time-Restricted Feeding and Its Effects on Obesity, Muscle Mass & Heart Health. Published 6/30/2016. Duration 1:31:33.
  • (TED) The brain benefits of deep sleep -- and how to get more of it | Dan Gartenberg. Explains the "Sonic Sleep Coach Alarm Clock" with a wave that enhances SWS (Slow Wave Sleep) or Delta-wave sleep. Note: This may be a paid commercial for the smartphone app.
  • Associations between sleep loss and increased risk of obesity and diabetes. The values observed after 5 days of sleep restriction [4 hours of sleep per night] were similar to those observed in older adults with impaired glucose tolerance,

Notes on circadian rhythm + melatonin

Rocked to sleep

  • Rocking synchronizes brain waves during a short nap. Published June, 2011. See also: Rocked To Sleep - Not Just For Babies Anymore. (a) Every one of the participants fell asleep more quickly during their rocking nap. (b) A majority (eight out of 12) said they found the rocking nap “more pleasant” than the nap on the stationary bed. (c) During the rocking nap, all of the sleepers moved more quickly from Stage 1 to Stage 2 of their sleep cycle. Stage 2 is where we typically spend half of our sleep time over the course of a night. (d) While rocking, sleepers showed significant increases in the types of brain-wave activity that are specifically associated with deeper (delta waves), more restful and more continuous sleep.
  • The researchers suggest that a rocking motion has the effect of helping to synchronize the brain for sleep — both to fall asleep more quickly and possibly to achieve longer periods of deep, uninterrupted sleep.

REM sleep (Reference)

  • While all four stages of sleep have their own distinctive characteristics, REM sleep is particularly unlike the others. Stages 1-3 of sleep, collectively known as non-REM (or NREM) sleep, are progressively deeper phases of sleep, characterized by often slower and more synchronized brain wave activity.
  • During REM sleep, the brain becomes very active, with brain wave frequencies that closely resemble the activity of a waking brain. Because of its striking similarity to a waking, “thinking” brain, it is sometimes referred to as paradoxical sleep.
  • In a typical night of sleep, this particular phase occurs at the end of the first sleep cycle, after the sleeper has moved through all stages of NREM sleep. After this first phase, the sleep cycle ends and a new sleep cycle begins. In each successive sleep cycle throughout the night, we spend progressively more time in REM sleep, as periods of REM within each sleep cycle grow longer.
  • Time spent in REM sleep changes over the human lifespan. Infants and very young children spend significant amounts of time in REM, about 50 percent of their overall sleep time. Adults typically spend about 20-25 percent of their total sleep time in REM.
  • Dreams. REM is an active stage for dreaming. ... The dreams that take place tend to be more vivid and complicated—and more likely to be remembered—than dreams that take place in other sleep stages. Much of what we consider typical dreaming—dreams populated with characters, events, and action, with visual and emotional texture and depth—appears to unfold during this stage.
  • Sleep paralysis. In REM sleep, the body enters a state of temporary paralysis, known as REM atonia. The major muscle groups are paralyzed, with muscle reflexes and tone suspended.
  • Reasons. We don’t fully understand the underlying reason for REM sleep, but decades of study strongly suggest that it delivers important developmental and restorative functions for the brain.

How much sleep is needed?

  • How Much Sleep Is "Enough"? From Mercola. Generally, 7-9 for adults, 7-8 for seniors and 8-10 for teenagers.
  • 5 Reasons Why You Should Take a Nap Every Day. Celebrity naps: Leonardo da Vinci took multiple naps a day and slept less at night. Napoleon was not shy about taking naps. He indulged daily. Albert Einstein napped each day—on top of getting ten hours of sleep each night. Thomas Edison was embarrassed about his napping habit, he also practiced his ritual daily. John D. Rockefeller napped every afternoon in his office. Winston Churchill’s afternoon nap was a nonnegotiable. He believed it helped him get twice as much done each day.
  • Reason #4. A nap reduces the risk of heart disease. Did you know those who take a midday siesta at least three times a week are 37 percent less likely to die of heart disease? Working men are 64 percent less likely! It’s true, according to a 2007 study published in the Archives of Internal Medicine (see Washington Post article: Midday Naps Found to Help Fend Off Heart Disease). “Taking a nap could turn out to be an important weapon in the fight against coronary mortality,” said Dimitrios Trichopoulos of the Harvard School of Public Health in Boston, who led the study.
  • How Much Sleep Do You Really Need to Work Productively? Interesting facts in the article. The trap of too little sleep: A sleep deprlved person can focus, but not refocus. "If we are sleep deprived, our brain can't refocus." On average, women need a tad bit more sleep than men. The average is 20 minutes more, but some women may need slightly more or less than this.
  • Give it up for the down state -- sleep | Sara Mednick | TEDxUCRSalon. Includes the negative effects of caffeine.
  • Metabolic consequences of sleep and sleep loss. In recent years, laboratory and epidemiologic evidence have converged to indicate that sleep loss may be a novel risk factor for obesity and type 2 diabetes. The increased risk of obesity is possibly linked to the effect of sleep loss on hormones that play a major role in the central control of appetite and energy expenditure, such as leptin and ghrelin. Reduced leptin and increased ghrelin levels correlate with increases in subjective hunger when individuals are sleep restricted rather than well rested.
  • Impact of sleep debt on metabolic and endocrine function. FINDINGS: Glucose tolerance was lower in the sleep-debt condition than in the fully rested condition (p<0.02), as were thyrotropin concentrations (p<0.01). Evening cortisol concentrations were raised (p=0.0001) and activity of the sympathetic nervous system was increased in the sleep-debt condition (p<0.02). INTERPRETATION: Sleep debt has a harmful impact on carbohydrate metabolism and endocrine function. The effects are similar to those seen in normal ageing and, therefore, sleep debt may increase the severity of age-related chronic disorders.
  • The Effects of Sleep and Sleep Deprivation on Metabolic, Endocrine And Immune Parameters. Sleep loss and sleep disturbances might contribute to the development of insulin resistance and type 2 diabetes either directly by their deleterious effect on the components of glucose regulation, or indirectly through appetite dysregulation, leading to weight gain and obesity, a major risk factor for insulin resistance and diabetes.