UNIT 5- RG 5A

Sleep and Dreams

Rhythm of Sleep

Circadian Rhythms occur on a 24-hour cycle and include sleep

and wakefulness

Controlled by the hypothalamus, specifically the suprachiasmatic nucleus (SCN)

●receives input from the eyes & is especially sensitive to the light dark cycles of day and night

● light signals the SCN to tell the pineal gland to stop release of melatonin…in darkness SCN no longer sends messages, increasing melatonin levels and sleepiness

Illustration © Cynthia Turner

2003

Under normal circumstances, the pattern undergoes daily readjustment by our exposure to light and by our

habitual routines

The Basic Sleep Cycle

The first 90-minutes of sleep

We experience 4-6 sleep cycles on an average

night.

Light sleep

Stage 1 – just drifting to sleep, may experience fantastic

images and/or auditory hallucinations

Stage 2 – more relaxed, clearly asleep – sleep spindles

(short bursts of brain activity) occur

Deep sleep (brain activity significantly slowed)

Stage 3 – transitional stage to deeper sleep

Stage 4 – deepest sleep of all, hard to awaken…only

occurs during the first few cycles of the night

Sleep Stages 1-4 --“Quiet Sleep”

REM Sleep – Paradoxical Sleep

After reaching the deepest sleep stage (4) the sleep cycle

starts moving backward towards stage 1. Although still

asleep, the brain engages in low amplitude, fast and

regular beta waves, much like awake-aroused state.

A person in this sleep phase exhibit Rapid Eye Movements (REM)

and reports vivid dreams.

Brain very active, yet major muscles in body relaxed/paralyzed.

How much sleep do we need?

We spend one third of our life sleeping.

Genetics influence exactly how much sleep we need…

however most humans sleep 9-10 hours if left

unhindered.

Adults need a bit less sleep than teenagers & children

do.

How much sleep do we need?

Our brain keeps track of

the amount of sleep we

get and does not let us

“make up” for lost sleep.

Once it’s gone, it’s gone.

You do, however, tend to

get more stage 4 and

REM.

Sleep Deprivation

1.difficulty focusing

2.diminished productivity

3.greater tendency to make mistakes

4.irritability and fatigue

5.diminished immune system

6.hallucinations (usually after 72

hours)

Sleep deprivation studies have shown us that sleep is a

necessary biological function. If we don’t get enough sleep,

we can experience…

Sleep Deprivation

The National Sleep Foundation found that over ½ of all

American’s are getting less sleep than they need!

Sleep Theories

1.Sleep Protects: Sleeping in the darkness when

predators loom kept our ancestors out of harms way.

2.Sleep Recuperates: Sleep helps restore and repair

brain (and body) tissue.

3.Sleep Helps Remembering: Sleep restores and

rebuilds our fading memories.

4.Sleep and Growth: During sleep pituitary gland

releases growth hormone. Older people release less

of this hormone and sleep less.

Sleep Disorders

1.Insomnia: difficulty falling asleep or

staying asleep

2.Narcolepsy: overpowering urge to fall

asleep that may occur while talking or

standing up Experience sleep attacks that usually last 5 minutes or

less…this can mean lapsing directly into REM sleep for

some people

Sleep Disorders

1.Night terrors: Sudden arousal from sleep and intense fear

accompanied by physiological reactions (occurs usually during

1st cycle)

Seems to be related to some fear the child has…but is not

the same as a nightmare (bad dream)…just see images

If not awakened, child often not remember in the morning

2.Sleep apnea: Failure to breathe when asleep

Wake up (100s) of times a night so

begin breathing again

Treatments include weight loss

and CPAP machine

Sleep Disorders

1.Sleepwalking: blank stare, move about in a slow/automatic

manner and may

try to eat, dress, or go to the

bathroom in the wrong place

occurs in stage 4 sleep

technical name…somnambulism

2.REM Behavior Disorder (RBD):

muscles not paralyzed in REM, allowing person to act out

their dreams (usually the vivid, violent, intense dreams)

Seen more often in middle-age/elderly men,

sometimes linked with Parkinson’s disease

Dreams

Usually story-like

unfolding mental

imagery – most

commonly dreams have

some degree of likeness

to daily activities, yet

tend to be more bizarre

and unrealistic

What do we Dream?

What are some common

themes in YOUR

dreams?

Have you ever had a

recurring dream?

Dreams Questionnaire…

●1000 Psychology Today readers

responded…o95% said they remembered their dreams

o39% said they could control their dreams

o68% said they had a recurring dream

o28% said they had died in a dream

o45% said they had dreamed about celebrities

Why do we dream?

1.Wish Fulfillment: Sigmund Freud suggested the

dreams provide a safety valve to discharge

unconscious wants & desires. oThe manifest content (remembered story-line) is a

censored version of the dream’s latent content

(underlying meaning of dream)

2.Information Processing: Dreams may help sift,

sort, and fix day’s experiences in our memories.

Why do we dream?

1.Physiological Function:

Dreams provide sleeping

brain with periodic

stimulation to develop and

preserve neural pathways.

Neural networks of

newborn are fast

developing therefore need

more sleep.

Why do we dream?

1.Activation-Synthesis Theory: Suggests that the

brain engages in a lot of neural activity that is

random. Dreams make sense of this activity. dreams are the

brain’s interpretations

of its own activity

SO… they mean

NOTHING!!!

Why do we dream?

1.Cognitive Development: Some researchers

argue that we dream as a part of brain

maturation and cognitive development.

All dream researchers believe we need REM sleep.

When deprived of REM sleep, and then allowed to sleep,

we show increased REM sleep called REM Rebound.

Dream Theories

Summary