Topic 10. Sleep.pdf

PT21203 Physiological Psychology Sleep Nur Farhana Ardillah Aftar, PhD Faculty of Psychology and Education Universiti Malaysia Sabah This work is licensed under a Creative Commons Attribution 4.0 International License. OUTLINE TOPICS TO...

PT21203 Physiological Psychology Sleep Nur Farhana Ardillah Aftar, PhD Faculty of Psychology and Education Universiti Malaysia Sabah This work is licensed under a Creative Commons Attribution 4.0 International License. OUTLINE TOPICS TO BE COVERED Rhythms of Waking Sleeping Stages of Sleep Functions of Sleep Sleep Disorders Rhythms of Waking and Sleeping  Early psychologists believed that cycles of wakefulness and sleep were dependent upon Introduction to external stimuli. Sleep Curt Richter (1922) conducted studies that implied that the body generates its own cycles of activity and inactivity Endogenous Rhythms ENDOGENOUS CIRCANNUAL RHYTHMS Some animals generate endogenous circannual rhythms, internal mechanisms that operate on an annual or yearly cycle Example: birds migratory patterns; animals storing food for the winter ENDOGENOUS CIRCADIAN RHYTHMS All animals produce endogenous circadian rhythms, internal mechanisms that operate on an approximately 24-hour cycle Sleep cycle Frequency of eating and drinking Body temperature Secretion of hormones Urination Sensitivity to drugs  Do we need circadian rhythm? SETTING AND Keep our internal workings in phase with the outside world RESETTING THE Generates a rhythm slightly longer than 24 hours without external cue. BIOLOGICAL It’s not perfect; needs resetting. CLOCK Zeitgeber: German term = “time giver” Stimulus that resets the circadian rhythm Examples of Zeitgeber: Light Tides Exercise Arousal activity Meals Temperature of environment Disrupted circadian rhythm: Depression, irritability, and impaired job performance.  Jet Lag Morning People & Shift Work Evening People Disruption of the circadian rhythms Sleep duration depends on when we Cycles can differ between people due to crossing time zones sleep and lead to different patterns of Due to a mismatch of the Night shifts people: adjust wakefulness and alertness internal circadian clock and incompletely Change as a function of age external time They feel groggy, sleep poorly Young children are morning Complains: Sleepiness during the during the day, and body people day, sleeplessness at night, and temperature peaks while sleeping Adolescents are often night impaired concentration instead of while working people Traveling west  “phase-delays” Best for adjustments: As an adult, it partially depends Traveling east  “phase-advances” Sleep in a very dark room during upon genetics the day. Work under very bright lights at night.  Suprachiasmatic Nucleus (SCN) The main control center of the circadian rhythms of sleep and temperature. MECHANISM OF Light: resets the SCN. Retinohypothalamic path; small branch of the optic nerve. THE BIOLOGICAL Genes Involved Two types of genes that produce certain proteins: CLOCK Concentrations of PER and TIM proteins promote sleep and inactivity. Light activates a chemical that breaks down TIM Mutations results in: Shorter than 24 hours circadian rhythm (seek to sleep early) Shorten the amount of sleep needed per day Impair people’s ability to rebound from temporary sleep deprivation Melatonin SCN control activity of the pineal gland. Pineal Gland secretes melatonin, a hormone that increases sleepiness Stages of Sleep  Sleep and Other Interruptions of Consciousness Sleep: a state that the brain actively produce Characterized by: decreased activity and decreased response to stimuli COMA VEGETATIVE MINIMALLY BRAIN DEATH STATE CONSCIOUS STATE Alternates between period of Extended period of sleep and moderate arousal. One stage higher than A condition with no sign of unconsciousness caused by During the more aroused vegetative state brain activity head trauma, stroke, or state, shows no awareness of Brief periods of purposeful No response to any stimulus disease. surroundings, and no actions 24 hours of no brain activity Low level of brain activity purposeful behavior Limited amount of speech before pronouncing brain Little or no response to Painful stimulus produces at comprehension death. stimuli least the autonomic Can last for months or Dies or begins to recover responses of increased heart years. within few weeks rate, breathing, and sweating. Can last for months or years. https://youtu.be/O8IOJLFH9f4  The electroencephalograph (EEG): discovery about stages of sleep, Assessing monitor brain activity during sleep sleep/wakefulness Records electrical potentials of cells and fibers in the brain areas nearest to each electrode. Allows researchers to compare brain activity at different times during sleep A polysomnograph is a combination of EEG and eye-movement records Source: Clinique Somnomed  STAGES OF SLEEP Slow-wave sleep Stage 2 (Stage 4) sleep Heart rate, breathing rate, Relaxation, K-complexes and brain activity Sleep Spindle decrease awake More slow waves than Relaxed wakefulness Stage 3 Stage 1 Slow-wave REM, sleep sleep “Paradoxical” Less brain (Stage 3) sleep activity, more than other stages of sleep. Heart rate, breathing rate, and brain activity decrease Fewer slow waves than Stage 4 STAGES OF SLEEP Source: OpenStax Source: OpenStax  Stages of Sleep Relaxed Stage Stage 2 Stage 3 & 4 REM & Stage 1 “Paradoxical” K-complex: sharp wave Steady series of alpha associated with temporary Slow-wave sleep: Heart Paradoxical: deep sleep waves: relaxation. inhibition of neuronal rate, breathing rate, in some ways and light firing brain activity decreases in others. Stage 1: irregular jagged, Spindles: burst of 12-to 14- Slow, large-amplitude Periods of rapid eye low-voltage waves. Hz waves for at least half a waves become more movement (REM) Brain activity is less than second. common. Postural muscles of the in relaxed wakefulness, Sleep spindles increase in Stage 3 fewer slow body are more relaxed. but higher than other number after new waves Combines aspects of stages. learning, number of sleep Stage 4 more slow deep sleep, light sleep; spindles correlates waves difficult to classify. positively with improvements in memory. After one hour of sleep, begin cycle: Slow-wave (stage 3 & 4)  Stage 2  REM Sequence repeats each cycle 90 minutes Functions of Sleep  Decreased sensory input to the cerebral cortex. Sleep & Inhibition Decrease readiness to respond to stimuli and decrease information transmitted to cortex. of Brain Activity Moderate responsiveness remains: Ex. Parents hearing crying infant. During lighter non-REM-brain responds to meaningful speech Any stage, intense stimulus produces arousal. There are active neurons, lesser than usual rate. How do we maintain a state of sleep? Inhibitory neurotransmitter GABA, Increased activity of axons that release GABA Weaker connections between parts of the brain. Sleep can be “local” in the brain Ex: sleep walking (active motor cortex), lucid dream (active frontal and temporal cortex), not able to move your arms (pons remains in REM; inhibit spinal neurons).  Because we get tired?  inhibitory process force you to become less aroused and less alert. Functions of sleep Energy Conservation: To save energy during inefficient times; activity would be wasteful and possibly dangerous. Mammal’s body temperature decreases; saving significant amount of energy Muscle activity decreases Animals increase sleep duration during food shortages.  Sleep ≈ Hibernation: Functions of sleep Decrease body temperature, drops heart rate, neuron cell bodies shrink, synapse disappear, regenerating later when body temperature increases. Animals come out of hibernation for a few hours, once every few days/weeks, and sleep. Retards or suspends the aging process. Period of relative invulnerability to infection and trauma.  Species Differences in Sleep: Specifies that are equally effective at all times of day, need less Functions of sleep sleep. Ex: Mexican cavefish, male sandpipers. Species abandon or decrease sleep under certain circumstances. Ex: Dolphins/whales after birth. Sleep on one side of the brain. Ex. Dolphins, whales, seals Swifts: fly out of next, 2 years, without landing on solid ground. Great frigate birds: most nights in the air Slow-wave sleep in one hemisphere, REM in both hemispheres, each sleep 11 seconds, total 45 minutes a night. Migrating birds: decrease need for sleep during migration Grazing animals vs carnivores  Sleep & Memory Improved memory Functions of sleep Learn something, then sleep/nap: memory solidifies, become better than it was before sleep. Hippocampus activity during sleep ≥ hippocampus during learning Brain replays experiences during sleep forms new dendritic branches and strengthens memories. Hypothesis on functions of REM 1. Strengthening memory 2. To get sufficient oxygen to the cornea of the eyes Biological Perspectives on Dreaming  Dream: represents brain’s effort to make sense of sparse and Activation- distorted information. Some part of the brain is active, but not others. Synthesis Cortex combines input with whatever activity available, and Hypothesis does its best to synthesize a story that makes sense to make sense of information. Examples: Dreams of falling or flying: lying flat on your back + active vestibular sensation= flying or falling. Dreams of trying to move but can’t: in REM, inactive motor cortex + major postural muscles are paralyzed. When dreaming, you can’t move, therefore you dream about not being able to move.  Dream: as thinking that takes place under unusual conditions. Neurocognitive 1. The brain gets little information from sense organ 2. Primary visual and auditory cortex have lower than usual Hypothesis activity 3. Other brain areas are free to generate images without constraints or interference. 4. Suppressed primary motor cortex & motor neurons of spinal cord: arousal can’t lead to action. 5. Suppressed prefrontal cortex: for working memory  we forget most dreams, lose track of what has been happening, no planning. 6. High activity in the inferior part of the parietal cortex: for visuospatial perception. Sleep Disorders  Periodic Limb Sleep Apnea https://youtu.be/Y-hz5zmcmmc Narcolepsy https://youtu.be/f6C6o4SLbTA Movement Disorder Frequent periods of sleepiness Repeated involuntary Impaired ability to breathe Attacks of sleepiness during the movement of the legs and while sleeping day sometimes arms during sleep. Breathless periods of a minute Occasional cataplexy: attack of Once every 20 to 30 seconds or so, they awaken gasping for muscle weakness when awake for minutes or hours vs breath. Sleep paralysis: inability to move occasional involuntary kick May not remember awakenings. while falling asleep or waking up. Consequences; sleepiness Hypnagogic hallucinations- during the day, impaired dreamlike experiences https://youtu.be/r7RuU3BMKP0 attention REM behavior disorder Night Terrors Sleepwalking https://youtu.be/2nc8jUOQA1c In REM, major postural Walking during NREM. Intense anxiety from which a muscles are relaxed and Usually not accompanied by person awakens screaming in inactive. dreaming. terror In REM behavior disorder: Not well understood More severe than a nightmare. move around vigorously; acting More common when people are Common in children out their dreams. sleep deprived or under Simple dream content. May injure themselves or other unusual stress. people/damage property. https://youtu.be/QDWiwjth5Qc Thank you! REFERENCES Freberg, L.A. (2019). Discovering Behavioral Neuroscience (4th Ed.) Singapore: Cengage Kalat, J.W. (2019). Biological Psychology (13th Ed.) Singapore: Cengage Pinel, J.P.J. & Brnes, S.J. (2018) Biopsychology (10th Ed.) Harlow, England: Pearson Tortora, G.J. & Derrickson, B. (2016). Principles of Anatomy & Physiology (15th Ed.). Hoboken, NJ: John Wiley & Sons, Inc.