Sleep and DreamsChapter 4

Definition: a person’s awareness of everything that is going on around h im or her at any given moment, which is used to organize behaviro.

Opposite of unconscious or semi-conscious!

Brings varied information to the surface, enabling us to reflect and plan.

Enables us to exert voluntary control and to communicate our mental states to others.

Focuses our concentration.

There is much more to information processing that consciousness.

Much of what we process is outside our awareness.

Beneath the surface, unconscious information processing occurs simultaneously on many tracks. (Note parallel processing.)

1. It lags behind the brain events that evoke it.

• You consciously experience the decision to move about .2 seconds before you actually move.

• But your brain waves jump about .35 seconds ahead of your conscious perception of the decision.

Unconscious brain activity precedes conscious awareness of a simple decision preceding an action.

Brain wave activity jumps just 1/3 second before the person consciously decides to move.

2. Consciousness is relatively slow (compared to the unconscious) and has limited capacity.

3. Is serial in nature. We can only think one thing at a time.

4. Consciousness is skilled at solving novel tasks requiring focused attention.

Is relatively fast and can run simultaneously on multiple tracks. Parallel processing.

We can perform familiar tasks automatically.

Biological Rhythms• Annual cycles• 28 day cycles• 7 day cycles?• 24 hour cycles• 90 minute cycles

Regular body rhythms that occur on a 24-hour cycle.• Body temperature• Alertness/thinking• Energy

Ultimately controlled by the hypothalamus

Light tweaks the circadian clock!

Light activates light-sensitive retinal proteins.

These trigger the suprachiasmatic nucleus.

That structure causes the pineal gland to increase or decrease melatonin.

Production peaks in the evening hours.

More light triggers the suprachiasmatic nucleus to signal the pineal gland to decrease melatonin production.

Less light stimulates more melatonin production, which helps aids sleepiness!

BUT, melatonin does not directly control sleep so other factors also affect sleep.

The chemical adenosine accumulates in our systems throughout the day, also contributing to sleepiness.

It dissipates while we sleep so we can wake up refreshed in the morning.

Caffeine can block adenosine’s activity, so we can stay up longer.

Serotonin also seems to play a role in sleepiness. More serotonin seems to produce increases sleepiness.

Body Temperature: as body temperature goes down, you feel sleepy.

Not sure what roles serotonin and body temperature play; the research is correlational.

Jet lag?

Sleeping late on the weekend mornings??

The effects of artificial light?

Sleep: periodic, natural, reversible loss of consciousness—as distinct from unconsciousness resulting from a coma general anesthesia, or hibernation.

The brain is still active while we sleep. About every 90 minutes we pass through a cycle of 5 distinct stages.

Just before sleep, Alpha waves show you awake and relaxed

Stage 1. Slowed breathing and irregular brainwaves. 5-10 minutes. You may experience fantastic images, resembling hallucinations, or a sense of falling/floating.

More deeply relaxed stage characterized by the periodic appearance of sleep spindles—bursts of rapid rhythmic brainwave activity. Lasts about 20 minutes.

Tensing and relaxing of muscles. Sleeptalking can occur in this state or

any other stage.

For a few minutes you go through this transition phase.

The brain begins to emit large slow delta waves.

More large, slow delta waves.

Stages 3-4 last about 30 minutes.

At the end of stage 4, children may wet the bed or begin walking in their sleep.

The auditory cortex will respond to sound stimuli. You can ignore common street sounds but wake up to your name.

You can sleep with babies (or pets) without rolling over them. (notable exception is when someone has used drugs.)

Rapid Eye Movement sleep, a recurring sleep stage during which vivid dreams commonly occur. Cannot be easily awakened.

Also known as paradoxical sleep because the muscles are relaxed but other body systems are active.

The inability to move in REM sleep is called REM paralysis.

As the night goes on, Stage 4 sleeps gets shorter and REM sleep gets progressively longer.

PET Scans show the visual and auditory cortexes are relatively active during REM sleep, but inactive during other stages.

The motor cortex is active, too, but the brain stem blocks its messages and muscles stay relaxed.

20-25% of our average night’s sleep.

REM sleep is characterized by dreaming, often emotional, story-like, more richly hallucinatory.

37% of people report rarely or never having dreams! They just don’t remember them.

REM sleep deprivation studies showed increased anxiety, irritability, and difficulty concentrating, as well as an increase in appetite.

Other researchers observed participants experiencing confusion, suspicion, withdrawal, and being “less well integrated and less interpersonally effective”. 

If deprived of REM sleep, people will actually return faster to REM sleep after going back to bed.

REM rebound: The tendency for a person (or animal) deprived of REM sleep to spend an increased proportion of sleeping time in REM sleep.

Newborns sleep about 2/3’s of the day!

Possible genetic factor in how much we need.

Teenagers typically need 8-9 hours a day. (Typically get less than 7!)

Adults need 6-9 hours a day.

People in industrial countries sleep less.

Some believe 80% of students are dangerously sleep deprived.

• Causes difficulty studying.• At high risk for accidents.• Tendency to make mistakes.• Irritability• General fatigue increases.

Slowed reaction times and increased errors on visual tasks.

Driving and piloting errors increase.

Suppression of the immune system.

Alters metabolic and hormonal functioning in ways that mimic aging, connected to obesity, hypertension and memory impairment.

Irritability, slowed performance; impaired creativity, concentration, and communication. (ADHD?)

Sleep deprivation might be disrupting hormones that regulate glucose metabolism and appetite.

Leptin, known as the “fullness hormone,” goes down with sleep deprivation.

Ghrelin, known as the “hunger hormone,” tends to be higher with sleep deprivation.

Sleep debt is the cumulative effect of not getting enough sleep. A large sleep debt may lead to mental and/or physical fatigue. There is debate in the scientific community over the specifics of sleep debt.

Current research indicates that the body’s maximum sleep debt is under 20 hours, no matter how many consecutive nights you’ve lost sleep.

It seems that sleep debt can only be paid off with minimum payments of 1-2 hours at a time. (i.e. not sleeping the whole the weekend!)

1. The Adaptive Theory of Sleep.

Evolutionary psychology points to man’s vulnerability at night against predators. Sleeping inside at night increased man’s survival!

2. The Restorative Theory of SleepThe theory of sleep proposing that sleep is necessary to the physical health of the body and serves to replenish chemicals and repair cellular damage.Replenishes chemicals; cellular damage repaired.Body growth—growth hormones from pituitary gland secreted during sleep.

In addition, it helps our memory. Sleep restores and rebuilds our fading memories of the day’s experiences/learning.

1. Insomnia—persistent problems in falling or staying asleep.

• 10-15% of adults complain of insomnia.

• Practice better sleep hygiene!—see page 147 in the book.

2. A sleep disorder characterized by uncontrollable sleep attacks, periodic, overwhelming sleepiness. May lapse directly into REM sleep.

• Cause: seems to be a relative absence of a hypothalamic neural center that produces hypocretin, an alerting neurotransmitter.

3. A sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.

• The person stops breathing; decreased blood oxygen arouses them to awaken and snort in air for a few seconds, then go back to sleep!

• This can repeat 400 times a night.

• Signs: tired and irritable, high blood pressure, snores at night, overweight.

4. A sleep disorder characterized by high arousal and an appearance of being terrified.

• Unlike nightmares, night terrors occur during Stage 4 sleep, within 2-3 hrs of falling asleep and are seldom remembered.

• Targets mostly children. They may sit up & walk around, talk incoherently, and appear terrified. They seldom wake up fully and don’t really remember in the morning!

5. Another stage 4 sleep disorder.

• Mostly in children, rare in adults.

6. A sleep disorder that occurs somewhere between wakefulness and Stage 1.

• The person feels awake, but experiences paralysis and fear.

A rare disorder in which the mechanism that blocks the movement of the voluntary muscles fails, allowing the person to thrash around and even get up and act out nightmares.

1. Freud’s theories. To satisfy our own wishes. Freud believed

dreams allow unacceptable wishes to be released from the psyche!

Manifest content: the actual content, what you remember

Latent content: the true meaning of the dream, which is hidden.

2. Activation-Synthesis HypothesisExplanation that states that dreams are

created by the higher centers of the cortex to explain the activation by the brain stem of cortical cells during REM sleep periods.

Basically, the brain tries to make sense of neural static. Neural activity is random but the higher brain centers try to make it cohesive, making a dream.

Hobson and colleagues upgraded the activation-synthesis hypothesis to:

The activation-information-mode model (AIM). Information that is accessed during waking hours can have an influence on the synthesis of dreams. As the brain makes up a dream, it uses meaningful bits of recent experience.