sleep and dreams: biological process

Question 1

endogenous pacemaker (SCN)

Answer 1

the sleep-wake cycle is controlled by a small area of the hypothalamus called the suprachiasmatic numbers (SCN), this is our internal biological clock

Question 2

SCN

Answer 2

the electrical activity of the SCN has an endogenous circadian rhythm , the SCN sends regular daily impulses via nerves to the pineal gland to produce the hormone melatonin

Question 3

melatonin

Answer 3

melatonin is the sleep hormone, high levels of melatonin stimulate sleep, evidence to support this: Siffre (1962) and Stephen and Zucker (1972)

Question 4

exogenous pacemaker

Answer 4

naturally occurring external factors that can affect our sleep-wake cycle the main one being light, the retina of the eye is also connected to the SCN via a nerve pathway, therefore light also affects the SCN and the pineal gland, light reduces melatonin production

Question 5

endogenous sleep regulating substances

Answer 5

a chemical called adenosine builds up in our cerebrospinal fluid during our waking hours which has the effect of increasing the pressure to sleep the more it accumulates

Question 6

adenosine

Answer 6

adenosine inhibits some neurotransmitters associated with wakefulness for e.g. serotonin. sleep pressure is only released by the act of sleeping itself, during which the levels of adenosine decrease to normal

Question 7

restoration theory

Answer 7

oswald (1966) restoration theory of sleep states that the main function of sleep is to allow the brain and body to carry out repair tasks such as repairing minor bodily injuries, removal of waste chemicals in the muscles, replenishing neurotransmitters and/or energy in the brain

Question 8

newborns

Answer 8

newborns can sleep for up to 20 hours a day, oswald points out that over 50% of this sleep is usually REM. rapid growth and development occurs immediately after birth, so increased REM would allow this growth to happen

Question 9

growth hormone production

Answer 9

there is an increase in growth hormone production during SWS 3 and 4, suggesting sleep has a key role in growth and repair

Question 10

rats

Answer 10

burn injuries on rats heal slower if they are sleep deprived

Question 11

neurotransmitters

Answer 11

oswald also argued that sleep allows the brain neurotransmitters to ‘normalise’, aiding psychological recovery

Question 12

sleeping longer

Answer 12

stressed or depressed people tend to sleep for longer periods than healthy people, this might explain why people generally report feeling better after a long sleep if they are ill

Question 13

evidence to support oswald

Answer 13

shapiro et al (1990), peter tripp

Question 14

stage 1

Answer 14

NREM stage between wakefulness and sleep, you are easily woken up at this stage and you can still hear noise around you. 5-10 minutes, 4-5% of total sleep, alpha brain waves

Question 15

stage 2

Answer 15

NREM light dreamless sleep. the persons muscles relax and brain slows, snoring may develop if throat and tongue muscles relax too much. sleep spindles may cause the person to twitch. 20 minutes, theta brain waves

Question 16

stage 3

Answer 16

NREM sleep spindles become less common. heart rate, metabolic rate, respiration rate, and temperature all fall. this is heavier but still dreamless sleep. you are now unresponsive and hard to wave up. 15 minutes, 4-6% of total sleep, theta into delta brain waves

Question 17

stage 4

Answer 17

NREM metabolic rate is at its lowest and arousal threshold is very high. this is very heavy sleep, skeletal muscles are slowly switched off, meaning movement is difficult, if woken the person will be extremely groggy and confused. 30 minutes, 12-15% of total sleep, delta brainwaves

Question 18

stage 5

Answer 18

REM the deepest form of sleep. they are almost impossible to wake and their muscles are so relaxed they are essentially paralysed, 20-25% of total sleep, brainwaves mimic those when awake

Question 19

strengths of the biological process

Answer 19

there is a lot of evidence to support the biological process explanation of the function of sleep and is therefore reliable. the methods used in studies that support the biological process are rigorous which makes the process more reliable. the biological process gives insight to way to help treat sleep disorders and has real world application

Question 20

weaknesses of the biological process

Answer 20

the biological process fails to take into account other explanations of sleep, there is evidence in the cognitive process to support sleep aids learning and memory, therefore the biological process is reductionist. research to support the biological process is mainly lab experiments, this means the process cant be used to explain behaviour in a real world setting as it lacks ecological validity

Question 21

two key brain structures that control biological rhythms

Answer 21

suprachiasmatic nucleus and the pineal gland

Question 22

michel siffre

Answer 22

evidence for the circadian rhythm. lived in total isolation for two months with no clocks or daylight, he quickly settled into a sleep/wake cycle of 24 hours

Question 23

stephan and zucker (1972)

Answer 23

lab rats housed with 12 hours of light and 12 hours of darkness were more active during the dark period however when the SCN was damaged, this pattern stopped concluding the SCN is a key pacemaker

Question 24

the SCN sends regular

Answer 24

daily impulses via nerves to the pineal gland to produce melatonin

Question 25

the retina of the eye is

Answer 25

connected to the SCN via a nerve pathway so light affects sleep

Question 26

light reduces

Answer 26

melatonin production

Question 27

caffeine, a common stimulant

Answer 27

blocks the effects of adenosine

Question 28

some sleeping pills

Answer 28

boost adenosine levels temporarily

Question 29

circadian rhythm

Answer 29

a body rhythm that cycles over 24 hours

Question 30

in anticipation of going to bed

Answer 30

body temp, blood pressure, and cognitive performance all decrease

Question 31

before dawn

Answer 31

metabolism is geared up in anticipation of increased activity when we wake

Question 32

evidence to support circadian rhythm

Answer 32

michel siffre (1962) stephan and zucker (1972)

Question 33

polysomnography

Answer 33

studying sleep using an EEG by recording activity of the brain

Question 34

order of sleep stages

Answer 34

1, 2, 3, 4, 3, 2, 5

Question 35

sleep cycles through the stages approximately

Answer 35

4 or 5 times a night

Question 36

according to oswald

Answer 36

REM sleep restores the brain, NREM sleep restores the body

Question 37

evidence of oswald

Answer 37

shapiro et al (1981) studies ultramarathon runners who slept for longer in NREM sleep after a marathon

Question 38

animal studies restoration theory evidence

Answer 38

many animals such as dolphins and seals have very little REM sleep with no adverse effects

Question 39

peter tripp

Answer 39

suffered hallucinations and delusions when he stayed awake for eight days

Question 40

randy gardner

Answer 40

showed that he suffered no ill effects of being deprived of sleep

Question 41

horne (1978)

Answer 41

reported that sleep deprivation did not interfere with the ability to play sport which contradicts oswald

Question 42

brain injuries

Answer 42

following brain injuries patients spend longer in REM for an average of 6 weeks suggesting the brain is being repaired, an application is when comas are induced