PSY Week 6 Part 3 Sleep
PSY Week 6 Part 3 Sleep PSY 151
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This 5 page Class Notes was uploaded by merlec16 on Wednesday October 5, 2016. The Class Notes belongs to PSY 151 at Wake Forest University taught by Ashley L. Heffner in Fall 2016. Since its upload, it has received 5 views.
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Date Created: 10/05/16
PSY Ch. 6 Sleep Notes p. 274-290 How – and Why – Do We Sleep? Microsleeps- barely perceptible and involuntary periods of sleep lasting between 3 and 15 seconds Humans spend about 1/3 of their lives sleeping How Much Sleep Is Enough? Total sleep deprivation- going entirely without sleep for 24 hours of more Impairment of motor skills, decision making, hallucinations, and memory performance Going without sleep for a period of days will not kill you Large majority of Americans believe they are getting enough sleep – actually sleep deprived Sleep Patterns Are Regulated by Two Processes Circadian pacemaker- governs each person’s internal “biological clock” Sleep homeostat- tracks the amount of sleep you have relative to the number of hours you have been awake The Circadian Pacemaker Circadian rhythm- any biochemical, physiological, or behavioral cycle that adheres to a near 24-hour schedule Circadian pacemaker- the “master control” for a person’s various circadian cycles, consisting of a group of neurons forming the suprachiasmatic nuclei of the hypothalamus Suprachiasmatic nuclei- (SCN) a group of neurons of the hypothalamus that constitute the circadian pacemaker Natural light is conducted from the retina via the optic nerve to the circadian pacemaker, conveying information about the time of day Light affects the production of hormones Melatonin- hormone of the pineal gland, stimulated by darkness and inhibited by light, which is associated with the onset of sleep o Produced during the periods of darkness The Sleep Homeostat Sleep homeostat- coordinated biochemical neural, and psychological functions that “keep track” of the amount of sleep a person has had relative to the number of hours of waking Sleep homeostasis- a balance between sleep and waking, governed by the sleep homeostat Sleep debt- when the sleep homeostat creates the urge to make up for lost sleep by sleeping longer or more frequently than usual Falling Asleep Is a Gradual Process Hypnogogia- a dream-like state at sleep onset during which a person may or may not be aware that he or she is experiencing hallucinations or delusions Myoclonia- jerking of limbs before sleep Sleep paralysis- sensation of being unable to move during periods of intense and often terrifying hallucination Sleep Comes in Two Types and Five Stages REM sleep- the fifth stage of sleep characterized by high levels of brain and nervous system activity and intensely vivid, hallucinatory dreaming (20%) NREM- sleep stages 2-4 characterized by cognitive activity, ordinary dreaming, and reduced brain and nervous system activity relative to REM (80%) Occurs over a greater portion of sleep time Sleep stages- 5 stages of sleep including a period of sleep onset, three periods of NREM, and one of REM sleep Each stage is associated with characteristic brain wave activity, and the stages are played out during the night in repeating pattern (the sleep cycle) Brain wave- characteristic electrical brain activity of various frequencies termed alpha, beta, theta, and delta Beta waves- the brain waves that predominate in waking states and are present in REM Alpha waves- predominate in relaxed, wakeful states while eyes are closed, and in sleep onset Theta waves- predominate at stage 2 and stage 3 sleep Delta waves- slow brain waves that predominate at stage 4 sleep 1. Stage 1 sleep- transition from relaxed wakefulness to onset of sleep 2. Stage 2 sleep- light sleep from which you can be easily awakened, but you will be unaware of environment as you sleep Sleep spindles K complexes 3. Stage 3 sleep- first stage of deep or “slow wave” sleep from which it is difficult to awaken May experience disorientation on awakening 4. Stage 5 sleep- REM Most intense and vivid periods of dreaming occur During REM sleep the nervous system revs up o Muscle tone suddenly decreases dramatically o Sleeper is effectively paralyzed and cannot move Sleep cycle- repeating patterns of stages 2-5 sleep that recurs four to six times throughout the night following sleep onset o One cycle lasts between 90 and 110 minutes The Function of Sleep Is Unknown We do not know WHY we sleep Rest and rejuvenate theory Sleep must be doing something beyond offering a person rest Possibly allowing the brain to consolidate and retain memories Possibly regulates the strength of brain synapses Do We Sleep to Remember? Memory processed seem to become profoundly impaired during sleep deprivation Sleep substantially improves memory for facts and skills one has learned Memories “replayed” during sleep Improves memories for emotional events Do We Sleep to Forget? In the absence of sleep, synapses would continue to become stronger, more numerous, and eventually take up too much brain space and require too much energy to maintain Sleep appears to prune back the strength of the synapses and their number, allowing the strongest ones to “scale back” to manageable size and the weaker ones to disappear all together What Are Dreams? Little agreement regarding the important questions of dreaming Sleep Mentation Includes Thinking and Two Levels of Dreaming REM does not necessarily produce dreaming Sleep mentation- any and all mental activity occurring during sleep, including “sleep thinking” and various levels of dreaming o Cognitive activity o Ordinary dreaming o Apex dreaming Cognitive Activity (“Sleep Thinking”) Sleep thinking- (cognitive activity) rational, directed thought occurring curing NREM sleep Ordinary Dreaming Average dream contains recognizable characters with realistic activities Ordinary dreaming- dreams depicting relatively realistic activities and recognizable characters o Majority of dreams that occur during NREM sleep Apex Dreaming Apex dreams- the most intense, bizarre, nonrational, and hallucinatory dreaming Characterized by the dreamer’s acceptance of wildly improbable events as being real Lucid dream- a type of apex dream where the dreamer becomes aware that he or she is dreaming Dreams Have Meaning to the Dreamer Dreams are the cerebral cortex’s attempt to make sense out of random electrical brain activity while it is operating without the help of neurotransmitters that characterize waking cognition Dreams are the brain’s attempt to solve problems during sleep or regulate mood carried over from the previous day Dream evolved to allow the dreamer to “rehearse” various sorts of responses to threatening situations Consist of content drawn from the person’s life history, circumstances, emotions, and subjective experience What Do People Dream About? th 1. Despite major cultural changes over the second half of the 20 century the dream life of young adults has remained essentially unchanged 2. There are stable cross-cultural similarities and differences in certain aspects of dream content 3. There is a strong continuity found between the content of people’s dreams and their waking thoughts 4. Sleeping environment can also effect the content of dreams What Are Sleeping Disorders? Sleep Problems and Sleep Disorders Are Not the Same Only 24% of the 75% of adult Americans defined by the NSF as having at least one symptom of a sleep problem agree that they do have a sleep problem Only 34% of Americans are at risk for any of the major sleep disorders Insomnia Has a Life of Its Own Insomnia- a chronic difficulty falling asleep, staying asleep, and/or being unable to obtain restful sleep Not the same as circadian rhythm disorder Exhaustion, irritability, isolation, and hopelessness about the situation ever improving pervade the sufferer’s entire day May have long lasting consequences Obstructive Sleep Apnea (OSA) Can Be Life-Threatening Obstructive sleep apnea- a sleep disorder caused by narrowing at various sites along the upper airway leading to repeated nightly episodes of inability to breath Most common of the sleep disorders Parasomnias Can Be Nightmarish Parasomnias- a group of sleep disorders characterized by unusual or bizarre physical behaviors, perceptions, dreams, or emotions during sleep Walk, talk, scream, eat, fight, urinate, grind their teeth, or have sex in their sleep REM-Sleep Behavior Disorder REM-sleep behavior disorder- a parasomnia where the sleeper is missing the muscle paralysis component of REM sleep and “acts out” confrontational and violent dreams Night Terrors Night terrors- parasomnia consisting of episodes during which the sleeper may suddenly sit up in bed screaming in fear, flail, or run as though pursued by a terrifying attacker o Night terrors are not caused by nightmares In the morning he or she likely will not remember the event Tend to occur during NREM sleep where dreaming is least likely to occur Sleep Walking Sleepwalking- (somnambulism) a parasomnia characterized by wandering often aimlessly, during late REM sleep Generally more benign Narcolepsy Destroys the Boundaries between Sleep and Wakefulness Narcolepsy- chronic disruption of the sleep homeostat and sleep cycle o Those suffering may feel the irresistible urge to sleep at any time, generally falling directly into REM sleep May begin to dream vividly the moment they fall asleep Associated with a dysfunction in the ability of the brain to produce hypocretin, a hormone that helps to govern the sleep cycle