ch 9 sleep and dreams

Circadian Rhythm

Internal biological clock. Our thinking is sharpest and memory most accurate as we approach our daily peak in circadian arousal

Different sleep stages occur every __

90 minutes

REM Sleep

Rapid eye movement sleep (sometimes called R sleep)

First stage of Non rem sleep is called

N1 sleep. In an unremembered moment, slip into sleep. Slowed breathing and irregular brain waves. N2 and N3 are the other two stages of non rem sleep.

N1: fleeting images

N3: minimal awareness

REM: a story-like dream

Suprachiasmatic nucleus (SCN)

part of the brain that decreases the production of melatonin due to bright like (screens, etc)

Why do we have a need for sleep

1. Sleep protects

2. Helps us repair/recuperate

3. Helps restore and rebuild our fading memories of the day’s experiences

4. feeds creative thinking

5. supports growth

Freud’s wish fulfillment

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).

Lacks any scientific support; dreams may be interpreted in many different ways

Information Processing

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

But why do we sometimes dream about things we have not experienced and about past events?

Physiological function

Regular brain stimulation from REM sleep may help develop and preserve neural pathways

This does not explain why we experience meaningful dreams

Activation synthesis

REM sleep triggers neural activity that evokes random visual memories, which our sleeping brain weaves into stories.

The individual’s brain is weaving the stories, which still tells us something about the dreamer

Cognitive development

Dream content reflects dreamers’ level of cognitive development, their knowledge and understanding. Dreams stimulate are lives, including worst-case scenarios

Does not propose an adaptive function of dreams

REM rebound

when people are deprived of sleep for a long time and finally able to experience undisturbed sleep, they sleep like babies

Hypnagogic state

pre sleep consciousness

Hypnic jerk (myoclonic jerk)

sudden quiver or sensation of dropping, as if missing a step

Hypnopompic state

post sleep consciousness

Desynchronized

When deprived of all environmental time, cues, sleep-wake, body temperature, and melatonin, circadian rhythms become desynchronized.

Jet lag

circadian rhythms are out of synchronization with daylight and darkness cues

Activation synthesis model

the brain imposes meaning on random neural activity. Theory that dreams are produced when the brain attempts to make sense of neural activity