Module 9: Sleep and Dreams

Sleep

A periodic, natural loss of consciousness (different from unconsciousness resulting from a coma, general anesthesia, or hibernation

Circadian Rhythm

Our biological clock/24 hour cycle; regular bodily rhythms

Examples of Circadian Rhythm

Temperature and consciousness

Ways our circadian rhythm can be altered

Age and experience

Sleeping Brain

Remains active + has its own biological rhythm

REM Sleep

Rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur (other body + brain systems are active during this time)

Other Names for REM Sleep

Paradoxical sleep because muscles are relaxed (except for minor twitches), and R sleep

How do sleep researchers measure brain wave activity, eye movements, and muscle tension?

By using electrodes that pick up weak electrical signals

Alpha Waves

The relatively slow brain waves of a relaxed, awake state

Microsleeps

Falling asleep for a few seconds

Hallucinations

Sensory experiences without sensory stimulation, like seeing something when there is not an actual visual stimulus

Hypnagogic Sensations

Hallucinations that occur before falling asleep

Sensations of falling or floating weightlessly before falling asleep are examples of…

Hypnagogic sensations

N2 Sleep

20 minutes of periodic sleep spindles; clearly asleep, but could be easily awakened

Sleep Spindles

Bursts of rapid, rhythmic brain-wave activity that aid memory processing

N3 Sleep

Deep sleep; slow-wave sleep, lasts about 30 minutes; brain emits large, slow delta waves; hard to awaken person

REM Sleep Stage

Occurs an hour after you first fall asleep; for 10 minutes, brain waves become rapid and sharp; heart rate rises, breathing becomes rapid and irregular; eyes dart around every half-minute, protective paralysis occurs, genitals may become aroused

What occurs when eyes dart around every half-minute?

These movements announce the beginning of a new dream

REM sleep tricks the brain into responding to dreams as if they were…

real

Delta Waves

The large, slow brain waves associated with deep sleep

How often does the sleep cycle repeat itself?

Every 90 minutes

Who experiences shorter, more frequent sleep cycles?

Young children and older adults

What happens to the different sleep cycles as the night goes on?

N3 grows shorter and disappears, REM and N2 periods get longer

How does REM offer therapy?

It calms the day’s emotions

Ways sleep patterns are influenced

Genetically, culturally, socially, and economically, and through stress and bright light (tweaks circadian clock)

Insomnia

Sleep pattern that results from DNA; recurring problems in falling or staying asleep

How does bright light tweak your circadian clock?

It activates light-sensitive retinal proteins; these proteins control the circadian clock by triggering signals to the brain’s suprachiasmatic nucleus

No light during the day=

disruption of circadian rhythm

What are the 5 reasons we sleep?

1. Sleep protects (survival)

2. Sleep helps us recuperate (repair, rewire, reorganize)

3. Sleeps helps us restore + rebuild fading memories of day’s experiences

4. Sleep feeds creative thinking (dreams inspire ideas)

5. Sleep supports growth

What results from sleep deprivation?

• Difference in mood (increased anger, fatigue, depression)

• Weight gain

• Affects hormones, metabolism, brain’s response to food

• Decrease in ghrelin, hunger-arousing hormone + increase in leptin (hunger-suppressing)

• Increase in cortisol, stress hormone that stimulates body to make fat

• Disrupts gene expression

• Enhances limbic brain responses to sight of food, decrease in layers around the cerebellum that help us resist temptation

Narcolepsy

Sleep disorder characterized by uncontrollable sleep attacks, sufferer may lapse directly into REM sleep at inappropriate times

Sleep Apnea

Sleep disorder characterized by temporary pauses in breathing during sleep and repeated momentary awakenings

REM Sleep Disorder

Sleep disorder characterized by acting out dreams while sleeping, through physical movements and vocal behaviors

Sleepwalking/talking

Regular activities while asleep; walking occurs during N3, while talking can occur at any stage

Night Terrors

Sleep disorder characterized by high arousal / appearance of being terrified, unlike nightmares, occur during N3 and are rarely remembered

Dreams

A series of images, emotions and thoughts passing through a sleeping person’s mind

What happens to the moments before we fall asleep?

They are lost from memory

What did Sigmund Freud believe about dreams?

Dreams are the key to understanding inner conflicts

Manifest Content

According to Freud, the symbolic, remembered storyline of a dream

Latent Content

According to Freud, the underlying meaning of a dream

Activation Synthesis Theory

The theory that dreams are the brain’s attempt to synthesize (make understanding of) random neural activity

REM Rebound

The tendency for REM sleep to increase following REM sleep deprivation

Cognitive Development Theory

The theory that dream content reflects dreamer’s level of cognitive development (their knowledge and understanding)

Freud’s Wish Fulfillment Theory

Dreams provide a “psychic safety valve”—expressing otherwise unacceptable feelings; dreams contain manifest (remembered) content and a deeper layer of latent content (a hidden meaning)

Information Processing Theory

Dreams help us sort out the day’s events and consolidate our memories

Neurocognitive Function Thoery

REM sleep allows the brain to consolidate (strengthen) memories and process emotional information