Dement & kleitman (1957) rem sleep and dreaming Physiological Approach

Think about a recent dream you have had Write a brief description and we will choose a few to ‘analyse’ . Dream analyser (Again, tongue in cheek!)

Sleep Sleep is defined as a regularly and spontaneously occurring altered state of consciousness that is characterised primarily by a loss of conscious awareness. We spend approximately one third of our life asleep and one fifth of our time asleep dreaming. Sleep does not mean the body and brain closing down and switching off as during sleep both body and brain are very active. Prior to the 1950’s no one had looked objectively at sleep and dreaming. The Dement and Kleitman study was a landmark study in that it enabled people to objectively look at what the brain was doing during dreaming.

Problems with investigating sleep: Sleep and dreaming Sleeping and dreaming are something we all do, however it is still something we know relatively little about. Investigating sleep can be problematic, together we’re going to make a quick mind map of the difficulties in investigating sleep. Problems with investigating sleep:

Why do you think we sleep?

Theories of why we need to sleep: Fill in your worksheet as we go along! Theories of why we need to sleep: Evolutionary theories: Sleep keeps the animal quiet and hidden which means that it is out of danger from predators. All species sleep, which suggests an evolutionary advantage. Recovery or restoration theories: The function of sleep is to restore the bodily reserves and to repair cells. Which theory do you find the most convincing?

The effects of sleep deprivation: What happens if we are deprived of sleep… Animal studies: In one study, rats were deprived of sleep. They all died within 33 days...

The effects of sleep deprivation: In another study cats were placed on a ‘floating island’ in a pool of water. If they fell asleep they would be tipped into the water. The cats eventually died 

Human studies The record for sleep deprivation is held by Randy Gardner. Aged 17, Gardner for stayed awake for 264 hours (11 days). He suffered: Blurred vision Incoherent speech Perceptual disturbances The first night after the deprivation he slept for 15 hours  mainly REM and stage 4 sleep (so this might suggest that REM and stage 4 sleep is the most important)

Other effects of sleep deprivation: Psychological Physiological Increased desire to sleep Short term sleep deprivation – no apparent major adverse effects if sleep caught up with the next night Difficulty in concentration Longer term – weight loss/weight gain Hallucinations/delusions May affect growth Forgetting May affect ability to heal

Theories of why we dream: Freud Dreams are an expression of our unconscious desires and conflicts. As they may be upsetting for us to deal with, they are expressed in symbols. Freud developed dream analysis to decode these symbols. What is a problem with this method? Problem Solving Some psychologists believe that dreams may be us considering our worries or problems from every day life.

Sleep and wakefulness In sleep we may ‘talk’ we may ‘walk’ Seem different but have a lot in common In sleep we may ‘talk’ we may ‘walk’ we have memories we can even plan things! Sleep patterns vary - average = 7/8 hours per night

Fill in your worksheet as we go along! Measuring sleep Brain activity can be recorded by an EEG (electroencephalogram) People may go to sleep labs where they are connected to EEG machines and brain activity is measured during the different stages of sleep.

Deeper than stage one, but we can still be woken easily Annotate your sleep stage graphs as we go: Stage 1: The ‘drifting’ stage It may occur when natural light fades which makes us produce a hormone called melatonin This hormone indirectly makes us sleepy, which is why we may start to feel drowsy when it gets dark Stage 2: Deeper than stage one, but we can still be woken easily Heart rate, breathing and brain activity slower than at stage 1 Stage 3: Deeper than stage 2  long, slow delta waves Heart rate, blood pressure and temperature are dropping at this point We are difficult to wake at this point Stage 4: Delta or quiet sleep It is hardest to wake us in this stage unless there is something relevant like an alarm clock or a baby crying Lasts for approx 30mins

A whole sleep cycle lasts for about 90 minutes. We move ‘down’ through all four stages before moving ‘up’ again REM SLEEP: When we have worked our way down the sleep stages 1 to 4) we then work our way back up from 4 to 2 At this stage, instead of going back to stage 1, we enter REM sleep Our eyes move back and forth beneath our eyelids Heart rate increases Our skeletal muscles are relaxed (paralysis) We dream during REM sleep REM sleep more frequent towards the morning Sometimes known as ‘paradoxical sleep’ because the body is in a state of relaxation and difficult to rouse – however, brain activity is similar to that of an awake brain

REM (Rapid Eye Movement) Sleep When we have worked our way down the sleep stages 1 to 4) we then work our way back up from 4 to 2 At this stage, instead of going back to stage 1, we enter REM sleep Our eyes move back and forth beneath our eyelids Heart rate increases Our skeletal muscles are relaxed (paralysis) We dream during REM sleep REM sleep more frequent towards the morning Sometimes known as ‘paradoxical sleep’ because the body is in a state of relaxation and difficult to rouse – however, brain activity is similar to that of an awake brain

Annotate your sleep stages diagram please. Extension task: How might you investigate the relationship between REM sleep and dreaming?

HOMEWORK: Complete the APRC template for Dement and Kleitman’s study, be prepared for a quiz at the beginning of the next lesson.