Body Rhythms and SleepBody Rhythms and Sleep

OutlineOutline

•• Biological RhythmsBiological Rhythms

•• Shifting Biological RhythmsShifting Biological Rhythms

•• Sleep: Forms and PhysiologySleep: Forms and Physiology

•• Sleep DisordersSleep Disorders

•• DreamsDreams

Understanding Biological RhythmsUnderstanding Biological Rhythms

•• Biological rhythmsBiological rhythms

–– A periodic, more or less regular fluctuation in a A periodic, more or less regular fluctuation in a

biological system; may or may not have biological system; may or may not have

psychological implicationspsychological implications

•• EntrainmentEntrainment

–– Biological rhythms are synchronized with Biological rhythms are synchronized with

external events such as changes in clock time, external events such as changes in clock time,

temperature, and daylighttemperature, and daylight

Endogenous Biological RhythmsEndogenous Biological Rhythms

•• Circadian RhythmsCircadian Rhythms

–– Occur about every 24 hoursOccur about every 24 hours

–– Example: The sleepExample: The sleep--wake cyclewake cycle

•• Infradian RhythmsInfradian Rhythms

–– Occur less often than once a dayOccur less often than once a day

–– Examples: birds migrating, bears hibernatingExamples: birds migrating, bears hibernating

•• Ultradian RhythmsUltradian Rhythms

–– Occur more frequently than once a day, about Occur more frequently than once a day, about every 90minevery 90min

–– Examples: stomach contractions and hormone Examples: stomach contractions and hormone levelslevels

Circadian RhythmsCircadian Rhythms

•• Circadian rhythms are cycles of activity and Circadian rhythms are cycles of activity and

inactivity generally lasting about one day inactivity generally lasting about one day

(from the Latin circa = (from the Latin circa = ““aboutabout”” and dies = and dies =

““dayday””.).)

•• Most peopleMost people’’s circadian rhythms, when s circadian rhythms, when

allowed to occur in an environment free of allowed to occur in an environment free of

familiar time cues, stabilize at a little over 24 familiar time cues, stabilize at a little over 24

hours.hours.

Circadian RhythmsCircadian Rhythms

•• Your degree of alertness depends where Your degree of alertness depends where

you are in your circadian rhythm.you are in your circadian rhythm.

•• Are you are morning person or an evening Are you are morning person or an evening

person?person?

–– Most young adults are evening people, or Most young adults are evening people, or

neutral.neutral.

–– Most people over the age of 65 are morning Most people over the age of 65 are morning

people.people.

Brain mechanismsBrain mechanisms•• The circadian cycle of sleep and wakeful states The circadian cycle of sleep and wakeful states

is governed by the is governed by the suprachiasmaticsuprachiasmatic nucleus nucleus

((““SCNSCN””.).)

•• This tiny structure at the base of the brain is This tiny structure at the base of the brain is

essentially your bodyessentially your body’’s s ““clock.clock.””

Circadian RhythmsCircadian Rhythms

•• SuprachiasmaticSuprachiasmatic nucleus (SCN)nucleus (SCN)

–– Influenced by external light and sends messages Influenced by external light and sends messages

to the pineal gland to cease secreting melatonin.to the pineal gland to cease secreting melatonin.

••Melatonin is produced during the night and Melatonin is produced during the night and

falls during the dayfalls during the day

InfradianInfradian Rhythms and MoodRhythms and Mood

•• Seasonal Affective Disorder (SAD)Seasonal Affective Disorder (SAD)

–– A controversial disorder in which person A controversial disorder in which person experiences depression during the winter experiences depression during the winter and an improvement of mood in the and an improvement of mood in the springspring

–– Treatment involves phototherapy or Treatment involves phototherapy or exposure to fluorescent lightexposure to fluorescent light

–– Evaluating frequency of and treatment for Evaluating frequency of and treatment for SAD is difficultSAD is difficult

Menstrual Cycles and MoodMenstrual Cycles and Mood

•• Question: Who believes the menstrual cycle Question: Who believes the menstrual cycle influences womeninfluences women’’s mood?s mood?

•• Physical symptoms are commonPhysical symptoms are common

•• Emotional symptoms are rareEmotional symptoms are rare

–– Irritability and depressionIrritability and depression

–– Fewer than 5% of women have Fewer than 5% of women have symptoms predictablysymptoms predictably

Research Conclusions about Research Conclusions about ““PMSPMS””

•• No gender differences No gender differences exist in moodexist in mood

•• There is no relation There is no relation between stage of between stage of menstrual cycle and menstrual cycle and emotional symptomsemotional symptoms

•• No consistent No consistent ““PMSPMS””pattern exists across pattern exists across menstrual cyclesmenstrual cycles

•• No connection exists No connection exists between between ““PMSPMS”” and and behaviourbehaviour

Why Women Overestimate Why Women Overestimate ““PMSPMS””

•• They notice depression or irritability when They notice depression or irritability when these moods occur premenstrually but these moods occur premenstrually but overlook times when moods are absent overlook times when moods are absent premenstrually premenstrually

•• They attribute irritability before menstruation They attribute irritability before menstruation to PMS and attribute irritability at other times to PMS and attribute irritability at other times to other reasonsto other reasons

•• They are influenced by culture and myths They are influenced by culture and myths about PMSabout PMS

•• CONFIRMATION BIASCONFIRMATION BIAS

Concept Check: MatchingConcept Check: Matching

•• UltradianUltradian RhythmsRhythms

•• Circadian RhythmsCircadian Rhythms

•• InfradianInfradian RhythmsRhythms

•• 2424--hour cyclehour cycle

•• LongLong--term cycle term cycle

(months)(months)

•• ShortShort--term cycle term cycle

(approx. 90 minutes)(approx. 90 minutes)

Concept CheckConcept Check

•• What is the name of the structure that What is the name of the structure that

controls sleep and wake cycles? controls sleep and wake cycles?

______________________

•• What hormone influences how sleepy you What hormone influences how sleepy you

are? ___________are? ___________

DesynchronizationDesynchronization

•• Under normal conditions, our bodyUnder normal conditions, our body’’s rhythms s rhythms

are governed by the SCN are governed by the SCN

–– Rhythms are synchronized with external and Rhythms are synchronized with external and

internal eventsinternal events

•• However, However, internal internal desynchronizationdesynchronization can can

occur, especially when people take airplane occur, especially when people take airplane

flights across several time zones. flights across several time zones.

Shifting sleep schedulesShifting sleep schedules

•• Mechanisms in the brain Mechanisms in the brain rely on light to reset your rely on light to reset your bodybody’’s clock and keep it in s clock and keep it in step with the step with the environment.environment.

•• If you travel between time If you travel between time zones, the light in your zones, the light in your new location will new location will eventually reset your eventually reset your clock, but you will be out clock, but you will be out of step for a while.of step for a while.

Shifting sleep schedulesShifting sleep schedules

•• Jet lagJet lag is the period of is the period of weariness and discomfort weariness and discomfort that occurs while your that occurs while your body clock is out of step body clock is out of step with your new time zone. with your new time zone. It is easier to adjust going It is easier to adjust going east to west than west to east to west than west to east.east.

••Jet lagJet lag affects energy level, mental skills, affects energy level, mental skills,

and motor coordination.and motor coordination.

Study: Flight AttendantsStudy: Flight Attendants

•• Flight attendants had Flight attendants had

–– higher concentrations of the stress hormone higher concentrations of the stress hormone cortisol in their saliva cortisol in their saliva

–– lower scores on visual memory testslower scores on visual memory tests

•• Prolonged and excessive Prolonged and excessive

cortisolcortisol levels levels

–– can result in neural deathcan result in neural death

••memory deficitsmemory deficits

Recovery from Jet LagRecovery from Jet Lag

•• Use bright lights to Use bright lights to ““resetreset”” the clock in the the clock in the SCN, SCN,

–– fool the brain into a new schedule. fool the brain into a new schedule.

•• Small amounts of melatonin on a Small amounts of melatonin on a controlled schedulecontrolled schedule

•• Sleep when the flight attendants tell you Sleep when the flight attendants tell you to sleepto sleep……

Shifting Sleep SchedulesShifting Sleep Schedules

•• Internal Internal desynchronizationdesynchronization also occurs when also occurs when

workers must adjust to a new shift. workers must adjust to a new shift.

–– Decreases in efficiencyDecreases in efficiency

–– Irritability and increased likelihood of accidentsIrritability and increased likelihood of accidents

Dangers of Shift WorkDangers of Shift Work

•• Examples of shift work: police officers, Examples of shift work: police officers,

emergencyemergency--room personnel, airline pilots, truck room personnel, airline pilots, truck

drivers, and operators of nuclear power plantsdrivers, and operators of nuclear power plants

–– Some famous accidents associated with internal Some famous accidents associated with internal desynchronizationdesynchronization: :

•• the 1989 Exxon Valdez oil spill off the coast of the 1989 Exxon Valdez oil spill off the coast of Alaska Alaska

••Three Mile Island and Chernobyl nuclear power Three Mile Island and Chernobyl nuclear power plant meltdownsplant meltdowns

Daylight Savings TimeDaylight Savings Time

•• Spring shift to Daylight Savings Time (and the Spring shift to Daylight Savings Time (and the

1 hr of sleep deprivation) led to a short1 hr of sleep deprivation) led to a short--term term

increase of the likelihood of accidental death increase of the likelihood of accidental death

((CorenCoren et al.et al.))

Measured over Measured over

3 years.3 years.

Concept CheckConcept Check

If you are a Vancouver based CEO, and you If you are a Vancouver based CEO, and you

need meet with an executive from India to need meet with an executive from India to

negotiate a tough deal, should you try to negotiate a tough deal, should you try to

meet the executive in Europe or in Japan?meet the executive in Europe or in Japan?

Why We SleepWhy We Sleep

•• The exact function of sleep is uncertain but The exact function of sleep is uncertain but sleep appears to provide time for: sleep appears to provide time for:

–– the body to eliminate waste products from the body to eliminate waste products from muscles muscles

–– repair cellsrepair cells

–– strengthen the immune system, and strengthen the immune system, and

–– recover abilities lost during the dayrecover abilities lost during the day

•• This is referred to as the This is referred to as the restorative theoryrestorative theory of of sleep.sleep.

Evolution and SleepEvolution and Sleep

•• The The evolutionary theory:evolutionary theory: evolution has evolution has

equipped all animals with a regular pattern of equipped all animals with a regular pattern of

sleep and wakefulness to help us conserve sleep and wakefulness to help us conserve

energy and avoid dangers.energy and avoid dangers.

•• This theory accounts well for differences This theory accounts well for differences

among species.among species.

•• Lions sleep about 20 hours a day while Lions sleep about 20 hours a day while

gazelles sleep much less. Why?gazelles sleep much less. Why?

Different Sleep PatternsDifferent Sleep Patterns……

Measuring Stages of SleepMeasuring Stages of Sleep

•• PolysomnographyPolysomnography is a is a comprehensive recording comprehensive recording of the physiological of the physiological changes that occur changes that occur during sleep during sleep –– EEG EEG �� brain activity brain activity

–– EOG EOG �� eye movementseye movements

–– EMG EMG �� muscle activitymuscle activity

–– ECG ECG �� heart rhythmheart rhythm

–– Breathing function is also Breathing function is also measuredmeasured

Stages of SleepStages of Sleep

•• There are There are multiple stages multiple stages of sleep, each of sleep, each with a distinct with a distinct pattern of pattern of brainwaves.brainwaves.

Alpha Waves Alpha Waves -- AwakeAwake

•• Initial (eyes closed): your brain emits bursts of Initial (eyes closed): your brain emits bursts of

alpha wavesalpha waves..

•• On an EEG recording, alpha waves have a regular, On an EEG recording, alpha waves have a regular,

slow rhythm and a high amplitude (height). slow rhythm and a high amplitude (height).

•• Gradually, these waves slow down even further, Gradually, these waves slow down even further,

and you drift off to sleepand you drift off to sleep

Stage 1 SleepStage 1 Sleep

•• When first dozing off, the sleeper enters When first dozing off, the sleeper enters

Stage 1Stage 1..

–– Gateway between awake and sleep, Gateway between awake and sleep, ““drowsy drowsy

sleepsleep””

–– Loss of muscle tone and conscious awareness of Loss of muscle tone and conscious awareness of

external environmentexternal environment

–– Light sleep, little eye movement, and a fair Light sleep, little eye movement, and a fair

amount of brain activity (amount of brain activity (““desynchronizeddesynchronized””

activity).activity).

Stage 2 SleepStage 2 Sleep

•• Stage 2Stage 2: a gradual transition begins into the : a gradual transition begins into the

synchronized, slow wave states.synchronized, slow wave states.

–– conscious awareness of external environment is conscious awareness of external environment is

gonegone

–– Less muscle activity; breathing and heart rate slowsLess muscle activity; breathing and heart rate slows

–– 4545--55% of total sleep time55% of total sleep time

Stage 3 SleepStage 3 Sleep

•• Stage 3Stage 3 is a transition into stage 4is a transition into stage 4–– The sleeper gradually moves back through The sleeper gradually moves back through

stages 3 and 2 and then has the first brief REM stages 3 and 2 and then has the first brief REM episode of the night.episode of the night.

–– only 3only 3--8% of total sleep time8% of total sleep time

–– Long, slow Long, slow delta wavesdelta waves

Stage 4 SleepStage 4 Sleep

•• Stage 4Stage 4 predominates in the first 3predominates in the first 3rdrd of the of the night and accounts for 10night and accounts for 10--15% of total sleep 15% of total sleep time.time.–– Almost entirely Almost entirely delta wavesdelta waves

–– Deepest stage of sleep Deepest stage of sleep –– hard to wake someone hard to wake someone up in this stageup in this stage

–– Night terrors and sleepwalking occur in this Night terrors and sleepwalking occur in this stagestage

•• Stage 5Stage 5, or , or REM sleepREM sleep

–– It is also referred to as It is also referred to as paradoxical sleepparadoxical sleep because because

there is physiological and brain wave activity there is physiological and brain wave activity

almost indistinguishable from the waking state. almost indistinguishable from the waking state.

Yet the large muscles of the sleeper are so relaxed Yet the large muscles of the sleeper are so relaxed

that the person is effectively paralyzed.that the person is effectively paralyzed.

–– Associated with dreamingAssociated with dreaming

–– More predominant in last 3More predominant in last 3rdrd of nightof night

–– Brain activity looks like that of Stage 1Brain activity looks like that of Stage 1

Rapid Eye Movement Rapid Eye Movement

(REM) Sleep(REM) Sleep

The Functions of REM SleepThe Functions of REM Sleep

•• New research suggests that REM sleep may New research suggests that REM sleep may

help to improve memory for difficult new help to improve memory for difficult new

tasks.tasks.

–– Students who sleep between learning and the test Students who sleep between learning and the test

score higher on memory tests.score higher on memory tests.

•• People deprived of REM sleep become quite People deprived of REM sleep become quite

irritable, anxious and distracted.irritable, anxious and distracted.

–– There is a There is a ““reboundrebound”” when finally allowed to when finally allowed to

indulge (more than usual amount of REM).indulge (more than usual amount of REM).

Stages of SleepStages of Sleep

Rhythms of SleepRhythms of Sleep

•• UltradianUltradian cyclecycle that recurs ~ 90 minutesthat recurs ~ 90 minutes

–– Nap for 20 or 90 minutes, not 60Nap for 20 or 90 minutes, not 60

••60 minutes is when deep sleep occurs60 minutes is when deep sleep occurs……groggygroggy

•• The REM periods last from a few minutes to The REM periods last from a few minutes to

as long as an hour, averaging about 20 as long as an hour, averaging about 20

minutes in length. minutes in length.

–– EEG during REM is similar to alert wakefulnessEEG during REM is similar to alert wakefulness

Typical NightTypical Night’’s Sleep for a Young Adults Sleep for a Young Adult

Concept Check: True or FalseConcept Check: True or False

•• Alpha waves are associated with being Alpha waves are associated with being awake.awake.

•• Delta waves are associated with Stage 2 Delta waves are associated with Stage 2 sleep.sleep.

•• The muscles are paralyzed during REM The muscles are paralyzed during REM sleep.sleep.

•• The rhythms occurring during sleep are The rhythms occurring during sleep are infradianinfradian rhythms.rhythms.

We need to sleepWe need to sleep

•• Sleep is necessary for normal Sleep is necessary for normal mentalmentalfunctioning. functioning.

–– After the loss of even a single nightAfter the loss of even a single night’’s sleep, s sleep,

mental flexibility, attention, and creativity are mental flexibility, attention, and creativity are

reducedreduced

–– Chronic sleep deprivation=high levels of cortisol Chronic sleep deprivation=high levels of cortisol

•• Impairs memoryImpairs memory

••Hallucinations and delusionsHallucinations and delusions

•• The amount of sleep varies from person to The amount of sleep varies from person to

person (not necessarily 8 hours)person (not necessarily 8 hours)

Sleep Disorders: InsomniaSleep Disorders: Insomnia

•• InsomniaInsomnia——difficulty in falling or staying difficulty in falling or staying asleep. asleep.

•• Many adults have occasional insomnia.Many adults have occasional insomnia.

•• It can be caused by a number of factors:It can be caused by a number of factors:

–– Psychological problems (depression and Psychological problems (depression and anxiety)anxiety)

–– Physical problems such as arthritisPhysical problems such as arthritis

–– Irregular or overly demanding work and Irregular or overly demanding work and study schedulesstudy schedules. .

Sleep Disorders: Sleep Sleep Disorders: Sleep

ApneaApnea

•• Sleep apneaSleep apnea––breathing periodically stops for a few breathing periodically stops for a few momentsmoments

–– Snoring is closely associated with this disorder. Snoring is closely associated with this disorder. Many sufferers from sleep apnea are obese men Many sufferers from sleep apnea are obese men who are usually middlewho are usually middle--aged or elderly.aged or elderly.

–– Two causes:Two causes:

••Abnormalities in the medulla (brainstem), Abnormalities in the medulla (brainstem), resulting in no signals for the lungs to breath resulting in no signals for the lungs to breath (uncommon)(uncommon)

••Efforts to breath continue, but a physical Efforts to breath continue, but a physical obstruction blocks air flow for a few moments obstruction blocks air flow for a few moments (more common)(more common)

Sleep Disorders: NarcolepsySleep Disorders: Narcolepsy

•• Irresistible and unpredictable daytime attacks of Irresistible and unpredictable daytime attacks of sleepiness lasting from 5 to 30 minutes. sleepiness lasting from 5 to 30 minutes.

–– 27,000 Canadians suffer from this condition, 27,000 Canadians suffer from this condition, many without knowing it. many without knowing it.

–– The cause may involve the degeneration of a The cause may involve the degeneration of a particular set of neurons in the hypothalamusparticular set of neurons in the hypothalamus

–– genetic factors seem to be involvedgenetic factors seem to be involved

Abnormalities of SleepAbnormalities of Sleep

•• ParasomniasParasomnias –– other unsettling occurrences other unsettling occurrences

during sleep include:during sleep include:

–– Sleep talkingSleep talking, which is not a symptom of any , which is not a symptom of any

mental or emotional disorder.mental or emotional disorder.

–– Sleep walkingSleep walking, usually found in children during , usually found in children during

stage 4 sleep. It is not the case that stage 4 sleep. It is not the case that ““you should you should

never wake a sleepwalker.never wake a sleepwalker.””

–– Night terrorsNight terrors, which involve awaking during slow, which involve awaking during slow--

wave sleep in an extreme panic. These are common wave sleep in an extreme panic. These are common

in children, less so in adults. in children, less so in adults.

Sleep Deprivation: Sleep Deprivation: ‘‘normalnormal’’ causescauses

•• Most common cause of sleepiness isMost common cause of sleepiness is——staying up staying up late and not allowing yourself to get enough late and not allowing yourself to get enough sleep at night. sleep at night.

•• TwoTwo--thirds of all thirds of all North North Americans get fewer than Americans get fewer than the recommended eight hours. the recommended eight hours.

–– Students get only about six hours of sleep a Students get only about six hours of sleep a night on averagenight on average

•• Most people need at least eight or nine hoursMost people need at least eight or nine hours……

Sleep AidsSleep Aids

•• Melatonin seems to promote sleep directly. Melatonin seems to promote sleep directly.

–– have been used to treat insomniahave been used to treat insomnia……mixed resultsmixed results

•• Benzodiazepines (reduce anxiety)Benzodiazepines (reduce anxiety)

•• Increase GABA releaseIncrease GABA release

–– Inhibitory neurotransmitterInhibitory neurotransmitter

““Sleep HygieneSleep Hygiene””((ZarconeZarcone & & StepanskiStepanski, 2000), 2000)

•• Reduce time spent in bed when not sleeping, Reduce time spent in bed when not sleeping,

particularly if feeling frustrated or worried about particularly if feeling frustrated or worried about

difficulty falling asleep.difficulty falling asleep.

•• Leave the bed if having difficulty falling asleep and Leave the bed if having difficulty falling asleep and

engage in a relaxing, distractive activity, such as engage in a relaxing, distractive activity, such as

reading or watching television.reading or watching television.

•• Establish and maintain a regular sleepEstablish and maintain a regular sleep--wake cycle.wake cycle.

•• Engage in moderate exercise daily but avoid Engage in moderate exercise daily but avoid

exercising right before bedtime.exercising right before bedtime.

““Sleep HygieneSleep Hygiene””

•• Establish a calm, quite bedroom setting. Remove the Establish a calm, quite bedroom setting. Remove the

bedroom clock from view at night.bedroom clock from view at night.

•• Ensure a comfortable bedroom temperature.Ensure a comfortable bedroom temperature.

•• Have a light snack before bed, but avoid excessive Have a light snack before bed, but avoid excessive

fluid intake.fluid intake.

•• Limit consumption of nicotine, caffeine, and alcohol, Limit consumption of nicotine, caffeine, and alcohol,

particularly before bedtime.particularly before bedtime.

•• Use sleep aids only occasionally.Use sleep aids only occasionally.

Concept Check: MatchingConcept Check: Matching

•• 1) Sleep Apnea1) Sleep Apnea

•• 2) Insomnia2) Insomnia

•• 3) Night terrors3) Night terrors

•• 4) Narcolepsy4) Narcolepsy

•• A) Awaking during slowA) Awaking during slow--wave wave sleep in extreme panicsleep in extreme panic

•• B) When breathing periodically B) When breathing periodically stops during sleepstops during sleep

•• C) Frequently and C) Frequently and unpredictably falling asleep unpredictably falling asleep during the dayduring the day

•• D) Difficulty getting to sleep or D) Difficulty getting to sleep or staying asleepstaying asleep

REM and DreamingREM and Dreaming

•• DreamingDreaming involves an involuntary involves an involuntary

conjuring up of images in a sequence in conjuring up of images in a sequence in

which the sleeper/dreamer is usually more which the sleeper/dreamer is usually more

a participant than an observer.a participant than an observer.

–– Generally occurs during REM sleepGenerally occurs during REM sleep

–– Can also occur during Stage 2Can also occur during Stage 2

The Content of Our DreamsThe Content of Our Dreams

•• It was once believed that dreams foretold It was once believed that dreams foretold

the future.the future.

•• But we now are certain that this is only by But we now are certain that this is only by

coincidence.coincidence.

•• The major controversy in psychology is The major controversy in psychology is

whether or not the dream tells us whether or not the dream tells us

anything about the dreamer. anything about the dreamer.

•• This is far from settled.This is far from settled.

4 Theories of Dreams and Dreaming4 Theories of Dreams and Dreaming

•• Dreams as unconscious wishesDreams as unconscious wishes

•• Dreams as reflections of current concernsDreams as reflections of current concerns

•• Dreams as byDreams as by--products of mental products of mental

housekeepinghousekeeping

•• Dreams as reflections of brain activityDreams as reflections of brain activity

Dreams as Unconscious WishesDreams as Unconscious Wishes

•• Sigmund FreudSigmund Freud concluded that our concluded that our

nighttime fantasies provide insight into nighttime fantasies provide insight into

desires, motives, and conflicts of which we desires, motives, and conflicts of which we

are unawareare unaware——a a ““royal road to the royal road to the

unconsciousunconscious..””

–– dreams express wishes and desires that have dreams express wishes and desires that have

been forced into the unconscious part of the been forced into the unconscious part of the

mind. mind.

Dreams as Unconscious WishesDreams as Unconscious Wishes

•• Freudian Freudian

interpretation: every interpretation: every

dream is meaningful, dream is meaningful,

no matter how no matter how

absurd the images absurd the images

might seem. might seem.

Freudian Dream InterpretationFreudian Dream Interpretation

•• Two types of content in dreams: Two types of content in dreams:

•• Manifest contentManifest content

–– Dream content that we consciously Dream content that we consciously

experience during sleep and may remember experience during sleep and may remember

upon wakening, upon wakening,

•• LatentLatent (hidden) (hidden) contentcontent

–– unconscious wishes and thoughts being unconscious wishes and thoughts being

expressed symbolically. expressed symbolically.

•• Problem: There are no concrete rules for Problem: There are no concrete rules for

interpreting dreamsinterpreting dreams……confirmation bias!!!confirmation bias!!!

Dreams as Reflections of Current Dreams as Reflections of Current

ConcernsConcerns

•• Dreams reflect Dreams reflect consciousconscious preoccupations of preoccupations of daily concernsdaily concerns

–– Including relationships, work, sex, or healthIncluding relationships, work, sex, or health

–– symbols in a dream do not disguise symbols in a dream do not disguise meaning; they convey it. meaning; they convey it.

•• Supported by findings that dreams are more Supported by findings that dreams are more likely to contain material related to a personlikely to contain material related to a person’’s s current concerns than chance would predict. current concerns than chance would predict.

–– e.g., teste.g., test--anxiety dreams in students anxiety dreams in students

Dreams as ByDreams as By--Products of Mental Products of Mental

HousekeepingHousekeeping

•• Unnecessary neural Unnecessary neural connections are eliminated connections are eliminated and important ones are and important ones are strengthenedstrengthened

•• The brain divides new The brain divides new information into information into ““wantedwanted””and and ““unwantedunwanted””

•• What we recall as dreams What we recall as dreams are only brief snippets from are only brief snippets from scanning and sorting that scanning and sorting that occurs during REM sleepoccurs during REM sleep

Dreams as Interpreted Brain ActivityDreams as Interpreted Brain Activity

•• ActivationActivation--synthesis theorysynthesis theory–– Dreaming results from the cortical synthesis and Dreaming results from the cortical synthesis and

interpretation of neural signals triggered by activity interpretation of neural signals triggered by activity in the in the ponspons (brainstem)(brainstem)

••Pons: sleep, eye movements, posturePons: sleep, eye movements, posture

––No psychological meaning to No psychological meaning to ponspons firingfiring

–– At same time, brain regions that handle logical At same time, brain regions that handle logical thought and sensation from the external world shut thought and sensation from the external world shut downdown

Activation Synthesis TheoryActivation Synthesis Theory

Concept CheckConcept Check

Are dreams Are dreams lessless likely to be reported likely to be reported

towards the beginning or the end of the towards the beginning or the end of the

night?night?

According to the activationAccording to the activation--synthesis theory of synthesis theory of

dreams, which brain area sends out signals that dreams, which brain area sends out signals that

are interpreted by the rest of the brain?are interpreted by the rest of the brain?