PY460: Physiological Psychology Chapter 9: Rhythms of Wakefulness & Sleep Rhythms of Waking & Sleeping Stages of Sleep and Brain Mechanisms Why Sleep? Why REM? Why Dreams?

Slide 2: Natural Cycles of Biological Activity [Clip: The Brain- Sleep & Circadian Rhythms] Curt Richter (1920’s)- biological beings have naturally occurring biological cycles largely independent of the outside world. Challenge to behaviorism in the mid-1900’s why? Endogeneous cycles- of evolutionary value anticipation of upcoming conditions migration mating storage “migratory restlessness” in willow warblers occurs despite lack of environmental cues (light)

Slide 3: Specific Endogenous Cycles Endogenous Circannual Rhythms internal cycles that prepares animal for seasonal changes storage of fats, hibernation, humans??? Endogenous Circadian Rhythms internal cycles (rhythms) that prepares animal for changes that last about a day. Most Familiar Rhythm? Sleep & Wakefulness! Others include: core body temperature, frequencyt of eating & drinking, hormonal secretion, chemical sensitivities (drugs).

Slide 4: Zeitgebers: Keeping Rhythms in Synchrony All rhythms typically stay in synchrony suggesting a “master biological clock” exists (more on this in a bit). We know that our free running rhythms are often greater than 24 hrs. (24.25- 24.75 hrs.). Why don’t we (and other animals) get “off-pace” with the 24 hours daily cycle? AH…LIGHT the primary Zeitgeber (say like a German)- resets the master clock. other “time keepers”- noises, meals, temperature variations

Slide 5: Mammoth Cave etc.- Altering the Biological Clock? What is humans traveled to a planet with a different daily cycle (say 20-30 hrs)? How would we adjust? Mammoth Cave study (1963). A month in a cave (temperature and light controlled). 28 hr days, (9 hrs sleep). What would happen to their cycle? Findings: Continued maintenance of the 24 hour clock… subjects could force themselves into the schedule but, bodies maintained original rhythms. Study 2: 12 volunteers in a cave… clock varied between 24-22 hours.. At 23 hrs most subjects adjusted, only 1 @ 22 hrs. Bottom Line- significant changes in daily rhythms very difficult to make

Slide 6: Disturbing the Biological Clock Our free running clock runs longer than 24 hrs, but our days are 24 hrs… daily readjustment keeps us in sync... What would changes might cause de-synchrony between biological clock & hourly clock? WEEKENDS (No.1)-- Fewer time constraints… Often follow bioclock---Go to bed later, sleep in…get up.. Reset clock.. Go to bed later than before.. Get up little later.. Reset clock-- by Monday, bioclock hours behind the hourly clock SHIFT WORK-- night shifts, or irregular pattern in schedule lead to irregular sleeping patterns, temperature often maintain daily pattern, health & safety issues. Particularly bright light somewhat effective in competing with day time light

Slide 7: More Disturbances in the Bioclock JET LAG- rhythm disturbance caused by crossing times zones.. Traveling west (PA to LA) (stay up later, sleep in… gain hours )(27 hrs… tend to be ok-- more natural to be awake a little later.. Sleep in) Traveling East (LA to PA) (lose hours).

Slide 8: Suprachiasmatic Nucleus- the bioclock Suprachiasmatic Nucleus- area in the hypothalamus, just above the optic chiasm (nerve). Rentinohypothalamic pathway Autorhythmic quality may drive circadian rhythms. Biological clock stops if damaged or Optic Nerve projecting to SCN is damaged Extremely sensitive to light (even in blind moles!) SCN reset to light Biochemical action unclear.. Protein production?

Slide 9: SCN & Melatonin Melatonin- hormone important in regulating sleepiness & wakefulness secreted near the end of a waking cycle.. A few hours before typical bed time. Pineal Gland- secretes melatonin release at the command of SCN. Taking melatonin supplements (.5 mg) in the afternoon---> phase-advances circadian rhythm (jet lag?) Taking melatonin in morning phase-delays circadian rhythm A note of warning-- little extended research in area.

Slide 10: The Brain During Sleep (NREM Sleep only) EEG- increased wave size= greater synchrony between two close sites on cortex. Provides an objective measure of sleep and wakefulness Stages of Sleep- characterized by a type of wave Awake/Relaxed- Alpha Waves, Beta Waves Stage 1: freq. irregular, jagged waves (Theta) Stage 2: Sleep Spindles (12-14hz) & K-complexes K-complexes evoke by sudden stimuli (noise etc) Stage 3 & 4: Slow wave sleep (SWS) (2hz waves) big slow waves (delta) indicating high synchrony reduced sensory input to cortex… “less noise” see wave and stone analogy (p. 254)

name the characteristics Slide 11: Synchrony & EEG Choose the stage & name the characteristics Big slow 1/2 sec waves; highly synchronous action Alpha & beta waves (smaller amplitude) regular and choppy respectively sleep spindles & k-complexes frequent here

Slide 12: REM Sleep/Paradoxical Sleep Michel Jouvet, Kleitman & Aserinsky- scientists notice that during certain intervals of sleep high levels of brain activity (almost looked awake) no bodily movement though, in fact most relaxed state of postural muscles rapid eye movement in humans increased “genital activity” called it “paradoxical” and “REM” sleep, respectively. REM sleep-- low voltage, irregular waves suggestive of considerable brain activity

Slide 13: Cycling through the stages Progression through the stages @ night. Stage 3 to 4 longest early on progressive lengthening of REM toward the final hours REM strongly associated with dreaming.. But apparently not the only dream stage

Slide 14: Brain Structures in Wakefulness & Arousal The Reticular Formation- structures whose length extends from the spinal cord up to the forebrain.. Widely connected to the sensory systems may easily respond to slightest sensory impulse Spontaneous pulsing activity regulating arousal even with little external stimuli Cutting through the midbrain immediately reduces arousa Pontomesencephalon- Locus Coeruleus- emits arousing bursts to meaningful events such as reinforcement/arousal and may assist in memory of important events. Inactive during sleep-->little memory??

Slide 15: “Arousing Brain Structures” continues Basal Forebrain (anterior and dorsal to hypothalamus) Damage leads to decreased arousal, impaired learning & attention most damaged by degradation of Alzheimer’s Acetylcholine- an arousing neurotransmitter in BF GETTING TO SLEEP- Inhibiting Arousal Systems Adenosine (declines during sleep) - a neuromodulator that accumulates over the course of the day and blocks ACh. Caffeine- blocks Adenosine--> incr. Arousal (ACh) interferes the whole day… even a morning cup of “Joe”. Prostaglandins- (decline during sleep)

Slide 16: Brain Functions in REM Sleep: PGO Waves The first indication of approaching REM sleep are short burst from the Pons, lateral Geniculate, & Occipital Cortex (PGO waves) (see text figure 9.12) LG and OC critical for vision processes-- REM primarily a visual phenomenon? First part of REM--- LG / OC manipulation Latter-- more thalamus than just LG and the cerebral cortex… becomes a less visual phenomena. Pons-- pulses related to sleep paralysis damage to Pons cell to the spinal cord leads to disinhibtion of behavior during sleep (fig 9.13).

Slide 17: Abnormalities of Sleep/Insomnias Causes: many caffeine, drugs, stress, temperatures Onset insomnia Maintenance Insomnia Termination Insomnia Irregularities in biorhythms phase delayed onset an issue phase advanced termination an issue

Slide 18: Other Abnormalities of Sleep Sleep Apnea- inability to breath during sleep-- cuts sleep times in half in worst cases…. Linked to obesity SIDS Narcolepsy- intrusion of REM into “wakeful”states sudden sleepiness during day cataplexy- muslce weakness while awake frequent sleep paralysis even during “twilight” states Hypnogogic hallucinations on early onset. PLMD- decr sleep paralysis (Pons?) REM Bhvr Disorder-act out dreams (damage to pons & midbrain) Night Terrors-screaming in terror during NREM sleep Talking in Sleep (REM or NREM sleep) Sleepwalking- strong genetic component awakening sleep walkers

Slide 19: What is sleep for? Theories on Function Repair & Restoration Theory- Sleep evolved to assist the body in repairing itself after the exertions of the day. Going without sleep-- psychological effects (what are they?) Physiological f/x: increased body temp, metabolic rate, appetite; decreased immune response. Evolutionary Theory of Sleep- a form of mini-hibernation… we sleep when food is scarce and danger is greater.. Conserves energy when we can’t replenish it easily or safely. Temp decreases, metabolism decreases Carnivores/Herbivores sleep patterns

Slide 20: The Function of REM- What is it good for? Abundance of REM during early childhood neuronal connections?? (see fig 9.17, pg276) REM varies from person to person.. It has been suggested we could go without it (Horne, 1988). So what if we do go without?? (Dement, 1960) Dement woke subject for a week every time went into REM stage effects: decreased time to REM sleep.. Up to an average of 26 times of waking per night by 7 day up from 12 on the first effects: increased anxiety, decreased concentration, personality change, increased appetite/weight gain. Cat research other hypotheses on roles of REM sleep REM assists in memory formation Increased oxygen delivery to retina’s

Slide 21: A Biological Perspective on Dreaming Freud- Dreaming symbolic of unconscious wishes (“wish fulfillment”) Activation-synthesis hypothesis- various external stimuli activate structures in the brain and are synthesized by the brain into a “story”. Is this sensible to you… how have external stimuli been incorporated into your dreams? Another version.. The brain is active during REM sleep but starved for stimuli.. In this absence---> borrows aspects from memory to construct a story. Flying sensations (vesitbular pulses) Slow movement dreams (postural muscles frozen) Clinico-Anatomical Hypothesis Dreams begin with arousing stimuli from the brain’s own motivations, memories, and arousal Does not compete with visual input or censorship by prefrontal cortex