psych-133-midterm-1.docx

Lecture 2: Sleep Basics - [Measurement \| Types: ] 1. Phenomenology: a. Loss of external awareness b. Disconnected thoughts → especially during transition c. Disorientation in time and space → losing track d. Images and dreams - Self reported experien...

Lecture 2: Sleep Basics - [Measurement \| Types: ] 1. Phenomenology: a. Loss of external awareness b. Disconnected thoughts → especially during transition c. Disorientation in time and space → losing track d. Images and dreams - Self reported experience 2. Behavior e. Horizontal position f. Low muscle tone g. 24hr (circadian) time (day vs time) h. Non-responsive, but reversible (rebound after deprivation) 3. Physiology: the gold standard i. Changes in the brain j. Changes in the body - [Polysomnography (PSG): Measuring Sleep ] --------------------------------------------- -- [Electroencephalography (EEG) ] --------------------------------------------- -- a\) Brain Waves b) ------------------------------------------ -- [Electrooculography (EOG): ] ------------------------------------------ -- a\) Eye movements b\)  ---------------------------------------- -- [Electromyography (EMG): ] ---------------------------------------- -- a\) Muscle tension b) ------------------------------------------------------ Sometimes need [1st night of adaptation] ------------------------------------------------------ - Types of Sleep - [Sleep Stages: ] a. Stage 1 b. Stage 2 c) Slow-Wave Sleep (SWS) ======================== ---------------------------------- ------------------------- ------------------- --------------------------- Rapid Eye movement sleep (REM) → [PGO waves] and transition in [dream sleep] ---------------------------------- ------------------------- ------------------- --------------------------- ------------------------------------- -- [REM sleep Paralysis: ] ------------------------------------- -- a. inhibited, causing paralysis b. Paralysis occurs to protect body from mind's dreams - NREM/REM only discovered in 1953 (Nathaniel Kleitman and Eugene Aserinsky) -------------------------- -- [Hypnogram ] -------------------------- -- ---------------------------------- --------------------------------------------- NREM → REM sleep cycle is around [90 (ninety) minutes in humans] ---------------------------------- --------------------------------------------- ------ ------------------------------------------- ---------------------------------------------------------------------------------------- More [deep NREM (slow wave sleep)] early in [sleep], more [REM sleep late] in [sleep] ------ ------------------------------------------- ---------------------------------------------------------------------------------------- - [Appearance: ]  1) Awake -------------------------------------- [Eyes:] open with blinks -------------------------------------- --------------------- -- [High ] --------------------- -- -------------------- -- [Low ] -------------------- -- b\) BrainWaves: times/sec or 15-30Hz) iii) desynchronized ------------------- c\) Muscle: strong muscle tone -------------- ----------------------- Stage 2 NREM (SLEEP SPINDLES AND K -------------- ----------------------- --------------------- -- [Slow ] --------------------- -- a. Eyes: eye movements stop (slowly roll in b. Brain waves: times/sec or 6-10Hz) -------- -------------------- Higher amplitude (larger) -------- -------------------- --------------------- -- [More ] --------------------- -- ----------------- ------------------------- ----- Special events: [K-complex] and ----------------- ------------------------- ----- Sleep Spindles ============== c\) Muscle: lowered muscle tone (dramatic reduction) 3. Stage 3 + 4 NREM (Slow wave sleep) ------- -------------------------------- ---------------------------------------- Eyes: [no eye movements] (contamination from EEG) → Right/lower ------- -------------------------------- ---------------------------------------- a. graph for EEG is much more scattered than higher b. Brain Waves -------------------------- -- [Very slow ] -------------------------- -- ------ ----------------------------- ---------- Slow [1-4 times/sec] or 1-4Hz ------ ----------------------------- ---------- i. ii) ---------------------------- -- [Synchronous ] ---------------------------- -- ------------------------ -- [Limited ] ------------------------ -- 4. REM sleep ------------------------------------------ Eyes closed but [horizontal] ------------------------------------------ ------------------------- -------------------- [movements] : back and forth → ------------------------- -------------------- -------- ----------------- Higher frequency (fast -------- ----------------- --------------------------- more than 10 times/sec or --------------------------- -------------------- -- [Low ] -------------------- -- look sort of like blinks b\) Brain Waves 10 Hz) ----------- ---------------------- ------------------ Muscles → [atonia] : no muscle tone ----------- ---------------------- ------------------ ii. iii) iv\) Desynchronized (like awake) Discussion 1 - Polysomnography: EEG (brain) + EOG(eyes)+ EMG (muscle) - X axis → time - Y axis → amplitude ------------------------------------ ---------------------------------------------- More power/higher amplitude → more activity/energy in that channel or frequency ------------------------------------ ---------------------------------------------- - [Power] : amplitude integrated across time - - Stage 4 SWS sleep ----------------------------------------------- The left and right channels move in parallel, ----------------------------------------------- -------------------------------- ------------------------------ brain activity of NREM sleep ( [delta and slow] -------------------------------- ------------------------------ - so you know it is not true REM sleep - normally , the channels show opposite polarity, with one eye going up and the other going down - Also EEG channels represent synchronized - [Young people have large amplitude slow waves than older adults ] - REM sleep --------------------------- -- [Phasic rem ] --------------------------- -- -------------------------------- in [phasic bursts] -------------------------------- -------------------------- -- [Tonic rem ] -------------------------- -- - Notice that the two eye channels go in opposite directions for true eye movements -------------------- -- [low ] -------------------- -- - [The EEG:] 1) --------------------- -- [high ] --------------------- -- ----------------------------- -- [more similar ] ----------------------------- -- - The EMG is characterized by extremely low or no muscle activity, lower than any other stage ----- -------------------------------------- ---------------- The [EEG activity is faster] than N3 and N4 ----- -------------------------------------- ---------------- - The eyes and brain tell you that it is not NREM sleep, and the muscle activity tells you that it is not wake - Stage 2 sleep - There are no eye movements - Stage 2 is characterized by the presence of two oscillatory events: the sleep spindle and the K complex ---------------------------------- -- [Circadian rhythms ] ---------------------------------- -- - Sleep is circadian → sleep at night, awake at day ------------------------ -- [Diurnal ] ------------------------ -- -------------------------- -- [Nocturnal ] -------------------------- -- ---------------------------- -- [Crepuscular ] ---------------------------- -- -------------------------- -- [Ultradian ] -------------------------- -- --------------------------- -- [ Infradian ] --------------------------- -- - \- - An organism must compensate for a drastic difference between night and day, so circadian rhythms are to deal with this - Example: camping in a dessert - [Advantages of rhythm: ] 1. Synchronize bodily functions 2. Avoid predation 3. Awake when food is available 4) Occupy a temporal niche, save energy --------------------------- -- -- -- [Zeitgebers ] --------------------------- -- -- -- - and peripheral body clocks for optimal efficiency and coordination of body-brain processes 1) Light 2. Food: important for peripheral clocks in the liver and pancreas 3. Exercise and activity: used in eldery to strengthen their circadian rhythm, which deteriorates with age, help recover from jet lag and shift work faster - [endogenous rhythm (without zeitgebers) is roughly 24 hours ] -------------------------- -- -- [Melatonin ] -------------------------- -- -- -------------------------------------------------------------------------------------- [Jet lag: Sleepiness during day] + [sleeplessness at nights] -------------------------------------------------------------------------------------- - Circadian disruption: cognitive deficits - [Flight attendants on short recovery crew had ] ------------------------ -------------------------------------- [smaller ] [right temporal volume ] ------------------------ -------------------------------------- -------------------------- -- [Increased ] -------------------------- -- ------------------------------------------------------------------------------------------------------ [Slower] reactions times and [less accuracy] on computer visual-spatial task ------------------------------------------------------------------------------------------------------ - Short recovery was less than 5 days for transmeridian flights that fly across 7 time zones, while the others had 14 days - Sleep deprivation is a likely carcinogen - Circadian rhythm and medicine - Blood pressure medications are most effective if taken between 6am-12am because blood pressure is highest - Cancer treatments are also more effective at certain times of day - Cancer drugs are have sweet spot or being most effective and least toxic - Sleep is controlled by circadian and homeostatic processes - [Two process Model: ] --------------------------- -- -- [Process S: ] --------------------------- -- -- Adenosine --------- ---------------------------- -- -- [NREM \> REM ] ---------------------------- -- -- b. Process S favors NREM sleep c. After night of sleep deprivation, S continues to build and leads to longer total sleep time and more NREM sleep --------------------------- -- -- -- [Process C: ] --------------------------- -- -- -- d. Process S regulates NREM and it is the priority stage of sleep 2) ------------------ --- ------------------------- circadian clocks → [Melatonin] ------------------ --- ------------------------- ---------------------------- -- -- [NREM \< REM ] ---------------------------- -- -- ----------------------------- -- [REM rebound: ] ----------------------------- -- d\) Controlled by the SCN - Sleep timing and stage are controlled by circadian and homeostatic processes - Two processes model not only explains the onset and offset - [A night of sleep deprivation increases sleep pressure, leading to: ] ------------------------------- -- [Increased NREM ] ------------------------------- -- Lecture 3: Circadian Rhythms ---------------------------------- -- [Circadian Rhythms ] ---------------------------------- -- ----------------------------------------- -- -- [Zeitgebers are exogenous ] ----------------------------------------- -- -- - [What circadian rhythms control: ] -------------------------------------------------- help [regulate] the sleep/wake cycle -------------------------------------------------- ### - Every living species shows a 24hr circadian rhythm ----------------------------- -------------------------------- ------------------------- Studied leaf movements of a [heliotrope plant] across the 24 hr period ----------------------------- -------------------------------- ------------------------- ------------------------------- -------------------------------------------- ------------- Discovered the persistence of [circadian rhythms in absence] of external ------------------------------- -------------------------------------------- ------------- - [Why we have circadian rhythm: circadian rhythm allow living species to synchronize (behavior and internal biology) with the 24hr light/dark rotation of the earth] - First demonstration - Jean Jacue d'Orto de Mairan (1729): french geophysicist - ### - Sleep exists in all animals regardless of evolution, but only birds and mammals have full blown REM sleep - REM is newer form of evolution - REM sleep evolves twice independently, once when seperating into birds, and secondly when going into mammals - [This fact tells two things ] 1. Relative to fish/amphibians, we can regulate our body temp, so perhaps the evolutionary pressure to create rem sleep came from need of thermoregulation so perhaps rem is related to thermoregulation 2. Metabolic regulation is perhaps related as thermoregulation is connected (more metabolic is more heat) so perhaps REM has to do with thermoregulation - First demonstration in humans - 1938: Kleitman and Richardson spent six weeks in Mammoth Cave, Kentucky (world's longest cave) (first to demonstrate the rhythm is endogenous) - At the time, some scientists believed our sleep/wake rhythm was controlled by sunlight - Examined what happened to their sleep/wake schedule in the total absence of light - Richardson (younger) developed a 24hr day (between 26-28hr/day) with 9hr sleep periods - Kleitman (older) had a harder adjusting and stuck close to 24 hr - Take home: human circadian clock generates a rhythm slightly longer than 24 ------------------- ----------------------------------------- hours when it has [no external cue to set it] ------------------- ----------------------------------------- ----------------------------------------------------------------------------------- Current estimate of circadian rhythm is [24hr 10 min] for most humans ----------------------------------------------------------------------------------- ----------------------------------------------------- -- -- [Mean rectal temperature across 24 hr ] ----------------------------------------------------- -- -- --------------------------------- ----------------- ----------------------------------------------------- [after sleep onset] and reaches its [peak about 6 hours before sleep onset] --------------------------------- ----------------- ----------------------------------------------------- - Rhythms of Waking and Sleep ---------------- ---------------------------------------------- ------------- rhythms is the [suprachiasmatic nucleus (SCN):] part of the ---------------- ---------------------------------------------- ------------- - The master 24hr (circadian) clock regulating biological - Uses melatonin ("Darkness Hormone") from the [pineal gland] -------------------------- -- [Melatonin ] -------------------------- -- - [It needs resetting everyday and this has to be done through zeitgebers] - -- -------------- -- pineal gland -- -------------- -- - Normally light hits the brain and melatonin is not released, but the moment it stops hitting it, the melatonin increases ------------------------------------------- ------------------------------------ Melatonin secretion usually begins around [two hours before bed] ------------------------------------------- ------------------------------------ - It cannot be released in light, only released in darkness - It remains high across the night and is suppressed during the day - Rhythms of waking and sleep -------------------------- -- [Zeitgeber ] -------------------------- -- - Since the endogenous (self-paced) biological clock is imperfect (24hr 10 min in humans), it needs to be reset to precisely 24 hrs - - Light is the most important zeitgeber because it is the most reliable twenty four hour signal - [Disrupting the circadian rhythm ] ------------------------ -- [Jet lag ] ------------------------ -- a. jet engines transport you through time zones much faster than our circadian rhythm can keep up with b. Characterized by sleepiness, during the day, sleeplessness at night c. Example: New York to London: when you fall asleep on the plane, you are woken when it is the morning destination in London, it is still 2 AM back in NYC d. For every hour that you shift out of your timezone, it takes about one day to readjust (NYC to London → 5 hr difference, so 5 days to adjust) -------------------------------------------------------------------------------------------------------------------------------- [Melatonin pills:] can [phase-advance] the [internal clock] (like winding a clock forward) -------------------------------------------------------------------------------------------------------------------------------- a. Secretion usually begins 2-3hr before bed b. Melatonin impacts the brain and body, including feedback to reset the sleep ---------------------------------------- --------------------------------------- wake rhythms through effect on the SCN [suprachiasmatic nucleus] ---------------------------------------- --------------------------------------- - Two process model of sleep-wake regulation - Circadian factor process (Process C): first of two governing sleep-wake rhythms - As the circadian rhythm increases, our drive to be awake increases and vice versa Lecture 4: Phylogeny - [Insects: ] ------------------------------------------------------------- [ Phenomenology] : cannot be tracked in insects ------------------------------------------------------------- ---------------------------------------------- [ Behavior] : (Dr. E. Rhoschild) ---------------------------------------------- a. Circadian timing ---\> awake during the day, not night b. Horizontal position c. Low muscle tone ----------------------------------------------------------------------------------------------- Birds have physiologically confirmed [cycles] of [NREM and REM sleep] ----------------------------------------------------------------------------------------------- d. Non-response (but reversible) - [Birds:] 1) ----------------- -------------- Unlike mammals, short cycles ----------------- -------------- ----------------------------------------- NREM sleep episodes: around 2.5 minutes ----------------------------------------- ---------------------------------------------------- REM sleep episodes: around [8 seconds] ---------------------------------------------------- ------------------------------------------------------------------------------------------------- Most birds do [not lose muscle tone] during REM sleep as consistently as mammals do ------------------------------------------------------------------------------------------------- ------------ ------------------------------------- --------------------------------------------------------------- Birds have [ unihemispheric sleep] : can sleep with halves the brain, with one half of the brain ------------ ------------------------------------- --------------------------------------------------------------- 4. can sleep while the other half stays awake a. This only happens for NREM sleep (but both sides can also have NREM) b. Both halves of the brain sleep during REM, never one side alone c. Can be: awake/awake, awake/NREM, NREM/NREM, REM/REM, NREM/REM 5. White crowned sparrow: military is looking to see if there are ways to skip sleep using this bird - [Reptiles, Amphibians and Fish ] ------------------------------------------------------------------------------------------------ Birds when having [SWS] will still have open eyes on that side, but will be closed ------------------------------------------------------------------------------------------------ 1. Amphibians, fish, reptiles show deep brain electrical activity indicative of NREM sleep → difficult to equate to birds and mammals a) 2. Most studies failed to find REM sleep in Amphibians and Fish 3. Arguable REM-like activity in reptiles, but this remains debated ### - Birds and mammals, that have REM sleep, evolved separately from reptiles - Thus REM sleep evolved twice in evolution: once in birds, and once in mammals - This means NREM sleep is the original stage of sleep - REM sleep came later in evolution - Clues as to the function of REM --------------------------------- -- [Thermoregulation ] --------------------------------- -- ------------------------------------- -- [Metabolic regulation ] ------------------------------------- -- ------------------------------------------------------------------------ --------------------- maintain a constant body temperature in the cold, but reptiles cannot, potentially showing ------------------------------------------------------------------------ --------------------- ----- ---------------------- The [ !Kung] ----- ---------------------- - Sleep on the ground or hard pallets - No pillows - Collective sleeping - Minimal bedding avoids insects - Frequently take afternoon naps, especially during dry, hot season - Monophasic or Biphasic: - Most pre-industrial hunter-gatherer tribes: ### - 30-60 min afternoon naps Biologically [hardwired dip] in [alertness] in the [middle of the day] in all - Are Western cultures returning to this pattern? Nap pods Lecture 5: Brain Mechanisms → Awake, NREM and REM - Neurochemistry: substance - [Three critical neurotransmitters for controlling sleep: ] 1. Acetylcholine (Ach) 2. Noradrenaline (NA) 3. Serotonin (5-HT) #### - Neuromodulators for sleep all come from the brain stem ---------------------------- -- [Active wake ] ---------------------------- -- - Distribution comes from brainstem, the activating center - The Neurochemistry of Wake-Sleep Cycle ------------ -- Quiet Wake ------------ -- - \- ------ -- NREM ------ -- ------- ------------------------------------ while [acetylcholine is not] ------- ------------------------------------ -------------------- -- -- -- [REM ] -------------------- -- -- -- ----------------------- -- [Cortex ] ----------------------- -- ------------------------- -- [Thalamus ] ------------------------- -- 2. active when high acetylcholine --------------------------------------------------------------------------------------- When stimulated, it is perceiving world and is alert during [wakefulness] --------------------------------------------------------------------------------------- ----------------------------------------------------------------------------- When asleep, it turns off and there is [no sensory information] ----------------------------------------------------------------------------- ---------------------------------------------------------------------------------------- When in REM, arch increases and [thalamus] is turned on again and we begin ---------------------------------------------------------------------------------------- -------------------------- -- [Brainstem ] -------------------------- -- - [AWAKE physiology → Information processing in awake: ] --------------------------------------------------------- --- ----------------------------------------- Brainstem turns on electrical [brain power] → [sensory processing begins] --------------------------------------------------------- --- ----------------------------------------- ------------------------------------------------------------------------------------------------------------------ Information reaches [cortex], which [leads to aroused and attentive state (wakefulness)] ------------------------------------------------------------------------------------------------------------------ 3. Information flood into brain from eyes, ears, nose, etc. activating the thalamus 3) - [NREM physiology: ] 1\) Brainstem turns off electrical brain power a\) NA and 5HT shutdown 4. Thalamus gate is closed thus information cannot enter brain a\) No sensory signal do not get past cortex does no processing 5. Asleep when there is no information feed to the cortex → firing is slow and synchronized with default activity only (no active processing) - [REM physiology: ] 1. Brainstem partly turns on power (ACh) 2. Internal stimulation of the sensory gate (thalamus) 3. Memories, emotions, visual center and motor, and motivations are activated in the cortex to lead to dreaming 4. [Prefrontal cortex is shut off, and the brain moves into being illogical, explaining state of dreaming] - [Ways to measure using brain scanners: ] 1. Positron emission tomography (PET) 2. Functional magnetic resonance imaging (fMRI) - [Parts of brain in REM sleep:] ------------------------------------------------------- [Cingulate cortex] : Emotional regulation ------------------------------------------------------- ------------------------------------------------------- [Motor cortex] : movement initiation (m1) ------------------------------------------------------- ----------------------------------------- ----------------------- --------------------------- --------------- [Lateral prefrontal cortex] : logical reasoning → [deactivated] during sleep! ----------------------------------------- ----------------------- --------------------------- --------------- ------------------------------------------------------------ [Occipital Cortex] : Complex visual processing ------------------------------------------------------------ ------------------------------------- [ Hippocampus] : memory ------------------------------------- - Visual, memory-filled motoric, emotional brain, without logical reasoning Discussion 2: - Chronotype MEQ scores (Morningness-Eveningness Questionnaire) - As we age, our chronotype tends to get earlier --------------------------------- --------------------------------------------------------------------- Causal-mechanistic explanation: [age related changes in the brain may alter circadian ] --------------------------------- --------------------------------------------------------------------- --------------------------------------------------------------------------------------------- Strength of zeitgebers can [influence variation within and across environments] --------------------------------------------------------------------------------------------- - Environment affects sleeping patterns ------------------------------------- -- [Sentinel Hypothesis: ] ------------------------------------- -- - Seen in modern hunter-gatherer peoples of Hadza in Tanzania - a synchrony of activity levels is produced by chronotype variation and this chronotype variation covaries with age - Awake at any given time makes the individual sentinel against predators - Guarantees presence of sentinel at any given time? --------------------------------------- -- [ Seehagen et al. 2014: ] --------------------------------------- -- - Previous studies found that a full night of sleep can improve memory for recently acquired information - [Experimental Questions: ] 1. Do daytime naps improve 6 and 12 month old infants' memory? 2. Does memory improvement from a nap persist after 24 hours? - [Methods ] - Infants were assigned to: 1\) Baseline a. Nap b. No nap 2\) learning a. Nap b. No nap - The memory task was an --------------------------------------------------------------------------------------------------- Memory was scored based on the number of [puppet actions repeated by the infant] (out --------------------------------------------------------------------------------------------------- - of 3) - [Results: ] ------------------------------------------------------------------- Only infants who napped showed [significant learning] ------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------- Infants remembered [more than 24 hours later] if they napped [after learning] ------------------------------------------------------------------------------------------------------- 3\) Both no nap and nap groups had sleep, but the nap group had a sleep episode very soon - Kurdziel et al. 2013: What is it about sleep during naps that enhances memory in children ------------------------------------------------------------------------------------------- - Preschool children 3-5 years old were given a spatial declarative memory task (remember where on a grid an object is located) - [Groups ] 1. napped 2. awake 3. napped with PSG - After an afternoon nap, children who had napped performed better than children who had not napped ----------------------------------------------------- -- -- [ Immediate] is [baseline ] ----------------------------------------------------- -- -- ------------------------ -- -- [delayed ] ------------------------ -- -- ------------------------------------------------------------- [24 hours] is after a night of sleep (next day) ------------------------------------------------------------- - \- - This difference persisted after 24 hours, meaning a normal night of sleep does not "even out" differences - The PSG was measured with children during the afternoon nap session  ----------------------------------------- --------------------------------------------------- Sleep spindles and memory enhancement → [NREM spindle density] was positively ----------------------------------------- --------------------------------------------------- - the more spindles, the greater the improvement during post-nap test ------------------------------------------------------------------------------------------------------------------------- Sleep spindles may act like a [file transfer mechanism] that help with [memory saving function] ------------------------------------------------------------------------------------------------------------------------- ------------------------------------ ----------------------------------------------------- [ Lemos et al. 2014: ] [Can naps enhance learning at school? ] ------------------------------------ ----------------------------------------------------- - [Questions: ] 4. Does napping also benefit middle school students? 2) Can naps enhance memory at school? - Students received a test in a subject they knew nothing about, they then heard a lecture on the subject - Students were either assigned to take a 2 hour nap condition or a normal class - Tested twice, pretest before lecture and a test 1, 2, or 5 days after lecture - Lecture was 15 minutes long and was about - Students were all at schools in Brazil - They were not aware they would be tested later in the week - The nap condition was defined by having a 2 hour opportunity to nap, but the researcher did not verify that the students had napped - Naps improve memory - Graphs show each time point (N) and the % change in test score - Students remembered information one day later, regardless of whether they had napped or not (about even) - Students tested after 2 and 5 days only did significantly better if they had taken a nap after the lecture - At 5 days, performance for non-nap students was at the same level as before the lecture, with an 83% decrease 1 day post lecture - The results suggest that daytime napping can enhance learning at school - The students who napped after the lecture had memory that persisted for several days after the lecture -------------------------------------- ----------------------------------------- ------------------------- Specifically, the nap after learning [protected the information] learned from forgetting -------------------------------------- ----------------------------------------- ------------------------- - Both groups learned the information, but only the non-nap group forgot most of - Ontogeny: sleep changes drastically across the lifespan in numerous ways - [WAKE:NREM:Ratio also change ] 1. Childhood: ???? vs Adult: 4NREM: 1 REM (stable ratio for rest of life) 2. As older, amount of total sleep decreases 3. Children have more deeper deep rem sleep and will wake up fewer times in the night 4. Pattern of sleep being as high polyphasic with large amounts → monophasic with less as we get older - Exam: Look at hypnograph what age do you think the person will be Lecture 6: Circadian Rhythms and Sleep Ontogeny - Two process model of sleep-wake regulation --------------------------------------------------------------- -- [This circadian factor or "process (Process C): ] --------------------------------------------------------------- -- - [As the circadian rhythm increases, our drive to be awake increases ] \- - Two process model of sleep-wake regulation --------------------------- -- [process S: ] --------------------------- -- - adenosine build up - The longer you're awake, the more pressure there is to sleep - When we sleep, we dissipate adenosine (decreasing sleep pressure/process S) - Adenosine decreases as we sleep and returns to S ----------------------------------------------------------------------------------------------------------------------------------------- [Caffeine blocks/masks] the [signal of adenosine] and fools your [brain into thinking you've been ] ----------------------------------------------------------------------------------------------------------------------------------------- - When caffeine is metabolized, it all hits at once ------------------------------------------------------------------------------------------------------------------------------ The [greater the urge] to sleep is the [greatest distance] there is between the process of S and the ------------------------------------------------------------------------------------------------------------------------------ - process of C \-  - [In sleep deprivation ] ------------------------------------------------------------------------------------------------------------------------------ you feel bad at [4-5 am,] because of [process C] is at it [lowest and Process C is high] ------------------------------------------------------------------------------------------------------------------------------ ----------------------------------------------------------------------------- You feel better at around [11Am] due to [Process C] ----------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------- Feel bad at [11PM] due to large gap between [Process C and S] and leads to oversleeping ----------------------------------------------------------------------------------------------------------------- - Process S could go on building forever - Sleep Ontogeny - [Different sleep pattern in stage of life: ] -- -- ----------------------------------------------- → [no structure of day and night] -- -- ----------------------------------------------- -------------------------------------------- 1 year old: [polyphasic sleep] -------------------------------------------- ------------- ------------------------------ 4 year old: [biphasic sleep] ------------- ------------------------------ --------------- -------------------------------- 10 years old: [monophasic sleep] --------------- -------------------------------- -------- --------------------------------- -------------------------- Adult: [monophasic sleep,] but shorter sleep period -------- --------------------------------- -------------------------- - Wake:REM:NREM ration changes - 20-90 years old: decreasing total sleep (40-50 years), stable of 4NREM1:REM ratio - As infant, 1:1 REM:NREM, 8 hours of each - 1-2 years: total NREM increases, while REM decreases - 2-20 decrease in total sleep - Sleep architecture changes - [Child (\~7 years) ] --------- -- Greater --------- -- -------------------- -- [Few ] -------------------- -- ---------- ------------------------ Somewhat [more REM] ---------- ------------------------ - Young Adults (\~25 years) \- - Mostly deep sleep/NREM in first half of night, then mostly REM in second - [ Eldery (\~75 years) ] ------------------------ -- [Absence ] ------------------------ -- -------------------------- -- [Increased ] -------------------------- -- ------------------------ -------------------- [Reduced ] [REM ] ------------------------ -------------------- Lecture 7: Creativity - Societal Anecdotes - The song yesterday came from to Mccartney when he was asleep - Thomas Edison: inventor - Thomas was a habitual napper, and had nap cots - Used sleep as a creativity tool - The genius gap: diet dreams - Examples in science - Mendeleev - Empirical, scientific studies - Numeric number reduction task: Tested if people could see trend in number strings and had to find a rule that let you find it faster - REM sleep or dream sleep tends to gift these types of benefits - Never told to stay awake on a problem, instead sleep on it - Power of sleep transcends cultural boundaries → idioms ### - There is a 3 fold increase in problem solving