Sleep and dreams: biological approach

Question 1

What is sleep

Answer 1

A condition of the body and mind that typically recurs for several hours every night: in which the nervous system is relatively inactive , eyes closed , postural muscles relaxed and consciousness practically suspended

Question 2

What is the circadian rhythm - what changes does it show

Answer 2

The circadian rhythm is a cycle over 24 hours of our bodies.
- humans show many changes over 24 hours , hormone levels ,body temperature , heart , respiration and metabolic rate

Question 3

Example of circadian rhythms : sleep-wake cycle

Answer 3

One example of the circadian rhythms is the sleep-wake cycle. This biologically controlled process ensures that we are awake and asleep at roughly the same times each day and night

Question 4

Which part of the brain controls our CR and how

Answer 4

• the area of the brain which controls our circadian rhythms is the hypothalamus , in particular the superchiasmatic nucleus (SCN)L
• the SCN lies where the two optic nerves (extending from the eye) meet:therefore the SCN is highly influenced by light: this is because it gets information about light levels from the nerve cells informing the brain when it is time to sleep .

Question 5

Experiments / evidence to show our circadian rhythm is controlled by the SCN

Answer 5

• Experiments have shown that where the SCN was destroyed in animals such as hamsters their sleep cycles have become disorganised.
• This is because the circadian rhythm (24 hour cycle of our body) is controlled by the SCN:
• shown by Ralph et al (1990) when an intact SCN was transplanted into hamsters with a damaged SCN , their circadian rhythm returned within a week to the circadian rhythm of the transplanted circadian rhythm : therefore showing it determined their circadian period.

Question 6

Hormone that triggers sleep

Answer 6

melatonin

• SCN controls melatonin - it informs the pineal gland
• pineal gland secretes the hormone, it is released when it starts to get dark
• makes us feel sleepy and eventually we fall asleep
• melatonin levels peak in middle of the night then decrease towards daytime

Question 7

How light regulates production of the hormone melatonin

Answer 7

• when darkness falls the SCN informs the pineal glad (situated in the centre of the brain and is about the size of a pea. )
• it produces hormone melatonin as it receives information from SCN relating to the zeitgeber of light
• this is because light regulates the production of the hormone melatonin which is produced between 9pm and 7:30 am and causes you to feel sleepy.

Question 8

• What is adenosine and how does it affect our sleep

- explain how caffeine interferes with sleep

Answer 8

• another chemical which affects sleep is adenosine. It builds up in our neurons during the day , causing us to feel more tired gradually through the day
• when we sleep the build up is cleared , then adenosine is replaced by energy in cells
• effects of adenosine help explain why caffeine interferes with sleep. This is because caffeine blocks adenosine receptors in neurons , making body less response to the build up of adenosine and reducing feelings of tiredness

Question 9

Sleep stages (sleep cycle) explained

Answer 9

There are many stages of sleep in a night’s sleep each of which occur more than once : there are 4 stages of non-REM sleep and the final stage is REM sleep.
Stage 1) stage is between sleep and wakefulness , heart rate slows , muscles relax , drifting off / woken easily. Hallucinations occasionally occur
Stage 2) begins around 15 minutes - a deeper sleep but can still be woken easily. EEG patters have larger and slower waves with burst of fast spiking activity (called sleep spindles)
Stage 3) at 20 mins : deep sleep , unresponsive to stimuli , heart rate, blood pressure and body temperature drop. EEG shows some large slow delta waves
Stage 4) at 45 mins : very difficult to wake. EEG shows only large slow delta waves. Sleepwalking can occur.

REM sleep: one stage of sleep
At 25 ish mins
- EEG activity shifts into a fast desynchronised pattern similar to being awake. The individual is hard to wake.
- muscles relaxed , person is paralysed
- DREAMS OCCUR
- Heart rate and respiration rate increase

Question 10

How many times are the stages of sleep cycled through

Answer 10

Around 5 times , and each cycle lasts around 90 minutes

Question 11

Key research study to understand function of REM asleep + if eye movements are connected to content of dreams
Aim

Answer 11

Dement and Kleitman 1957
Aim : to provide study of the function of REM sleep , and where rapid eye movement are connected to the content of sleep
Does dreaming take place during REM ?
Are participants aware of the length of dreams - 5 or 15 minutes ?
Does eye movement direction relate to dream content ?

Question 12

Dement and Kleitman (1957). Explain :

• participants
• research method
• procedure

Answer 12

Participants : 7 adult males and 2 adult females all volunteers. (Volunteer sampling)
Research method : laboratory research using observation
Procedure:
- subject slept individually in dark room in lab after normal day of activity
- alcohol and caffeine were avoided during the day
- electrodes connected on scalp to measure brain waves and near the eyes to register eye movement
- subjects woken various times during night by loud doorbell noise , and immediately reported into a recording device whether they had been dreaming ( dreaming only counted if a fairly detailed dream was reported)

Question 13

The different sections to the study and their results

Answer 13

Study 1) subjects woken by bell , rem and non rem movement recorded and reports compared to see if they were dreaming
Study 2) subjects woken after 5 mins and 15 mins after REM sleep began , and were asked to estimate duration of their dream
Study 3) subjects woken when eye movement occurred and eye direction was recorded - then were asked exactly what they had dreamt

Findings :
Study 1) significantly more dreams reported in REM awakenings (80% had dreamt on REM awakenings and 9% on non REM)
Study 2) they said their dreams were shorter if they were woken 5 minutes after the start of REM sleep compared to being woke 15 mins after it started. 5 mins : 75% participants were correct in matching the duration of their dream to the length they had shown in rem sleep. 1t mins : 63% were correct
Study 3) patterns of REM and the content of dreams showed a relationship
Vertical rem : associated with dreams of looking up and down at cliff faces , ladders and basketball nets
horizontal rem : was associated with dreams of two people throwing tomatoes at each other

Question 14

Evaluation of dement and kleitman study - strengths and weaknesses

Answer 14

Strengths
- this was first scientific (objective data collected ) research into dreaming -before this research on dreams has been to as participants of their dreaming (subjective data)
- research provides support for the idea that dreams can be studies in an objective way - so can be opened up for the subject of further research- evidence that REM sleep is dream sleep has been supported by further research after this
Weaknesses
- dreams are recalled easier in REM than non rem sleep , perhaps dreams occurring in deeper sleep are just more difficult to record
- small sample size and mostly men , this means it showed a lack of generalisability - also was focused on adults so can’t be generalised to children
- lab experiment - lacked ecological validity and was not natural, therefore could have affected the quality of sleep or the content of dreams.

Strength example : a strength of D+K study is that it was a lab experiment whuch was an advantage as they had more control over extraneous variables. For example they were able to control the extraneous variable of alcohol and caffeine. They did this by instructing participants mot to drink alcohol or caffeine on the day if the study. This is because both of these things can affect your sleep. The reason for avoiding caffeine was because it attacks to adenosine receptors , blocking adenosine receptors so reducing feelings of tiredness.

A weakness is that :the lab experiment : has low ecological validity , meaning it doesn’t reflect a real life setting. This is because they had to sleep in a sleep lab and slee with electrodes attached to their head near their eyes. This meant that they were in an un natural setting which would be as they would be sleeping if they were at home , especially as things such as noise and light was controlled by the experimenter. Also with the electrodes, it may have been harder to sleep as it would be uncomfortable , this may have made it harder to sleep and therefore affected results.

Question 15

Explain research method / procedure of dement and Kleitman study 1957

Answer 15

1) participants were instructed not to drink alcohol on the day of the study. This is because both caffeine and alcohol can affect sleep. Ebrahim (2013) found that the amount of time spent in REM after drinking alcohol was reduced by 10%
2) electrodes are connected near the eyes. This is because eye movement patterns were related to dream content therefore they were put on to register eye movement. Dement and Kleitman found that vertical REM was associated with dreams of looking up and down ar cliff faces , ladders and basketball nets and horizontal rem was associated with two people throwing tomatoes at each other

Question 16

Mandatory theory : oswalds theory

• name and date
• what it proposed

Answer 16

Oswalds restoration theory of sleep (1966)
Proposes that sleep restores the brain and the body
Specifically :
- Non rem sleep restores and repairs physical damage through the day eg bruises , cuts , damaged tissue , bones , muscles by restoring depleted energy and reserves of hormones
- REM sleep replenishes and renews brain chemicals. Chemicals such as adenosine are cleared from the brain

Question 17

supporting studies of oswalds theory (1966)

- Shapiro

Answer 17

The Shapiro et al (1981) experiment supports restoration theory.
- This is as in this study of runners : it was found the participants sleep lasted on average 90 minutes longer than usual over the 2 nights after an ultramarathon: particularly non REM sleep rose from 25% to 45% of sleep. Respiration theory supports that his is because of the idea that the body needs more sleep to repair itself after injuries or damage.

Question 18

It is important to distinguish between bodily restoration and brain restoration.
Talk of Hobson and then Horne and Harley

Answer 18

• Hobson (2005) believed that sleep is entirely for the brain
• Horne and Harley (1988) however believed that the longer sleep in the Shapiro study was caused by the warming of the brain. To test this they heated peoples heads using a hairdryer , and four of their six participants were found to have a longer period of non REM sleep.
• this finding contradicts the idea that sleep repairs the body

Question 19

Theory supporting restoration theory 
Dement 
- aim 
- procedure 
- results  
- conclusion + control

Answer 19

Dement (1960) effect of dream deprivation
Aim : to observe effects of REM sleep deprivation in the lab
Procedure : dement observed 8 men during sleep in the lab for 4-7 days consecutively. Participants where women whenever eye movements indicated REM sleep. They were kept awake after this for a few minutes then returned to sleep.
Results : first night average number of REM sleep awakenings was 12 times. Last night average was 26 times
Conclusion : there were behaviour changes after REM sleep deprivation - including irritability , increased anxiety , reduced concentration and mild personality changes. As REM sleep deprivation increased,participants all increased their attempts to enter or achieve some REM asleep
A control condition showed that it was not the sleep deprivation in general but specifically REM sleep deprivation

Question 20

Evidence for restoration theory

- Peter Tripp

Answer 20

Peter Tripp (1959)
Aim 
Procedure 
Results 
Conclusion 

• the Peter Tripp case study (1959) supports the restoration theory. This is because the lack of REM sleep had caused changes in peters behaviour. He started to become more mean - for example when he behaved aggressively towards his barber, and this was not normal for him as he was known as a kind man. Restoration theory would explain that this was because his brain didn’t have the time to flush out and restore essential chemicals such as the hormone adenosine, during periods of REM over 8 days of staying awake.

Question 21

summary of reasons supporting oswalds restoration theory

Answer 21

• Sleep deprivation : studies of sleep deprivation (specifically REM sleep deprivation ) show brain function deteriorates (Dement 1960) (Peter Tripp 1959)
• sleep patterns after major periods of exercise: a number of pieces of research have shown that excessive exercise increases the amount of time spent in nREM. (Shapiro et al 1981)
• changes in sleep patterns over lifespan: babies spend 18 hours every 24 hours asleep - and half of this is REM sleep. By age of 5 this falls to about 8 hours sleep and only 2 in rem, which remains the same for rest of life. This can be explained to be because the first 5 years of life are very important for brain development where a great deal of protein synthesis is necessary for cell growth - so makes sense a younger child requires more REM sleep than an adult if REM is important for brain processes.
  Sleep patterns and illness : total sleep time increases during periods of illness - sleep therefore is required for improved immune system functioning. Therefore , NREM sleep restores biological processes that have deteriorated
  Sleep patterns following brain injury - people recovering from brain injury , ECT and drug withdrawal tend to spend more time in REM during recovery. This suggest that REM sleep is important for proper brain functioning

Question 22

Evaluation restoration theory

Answer 22

Look at pages 30-31 of practice and pass

Question 23

Factors affecting sleep

Answer 23

• Drugs : caffeine / alcohol / antihistamine
• light
• shift work and jet lag

Question 24

How does 
- caffeine 
-alcohol 
- antihistamine 
affect sleep

Answer 24

• adenosine builds up during day , makes us tired. to a nerve cell caffeine looks like adenosine. Caffeine binds to adenosine receptors, however caffeine doesn’t slow down the cells activity as adenosine would, it instead speeds them up The cells can no longer identify adenosine because caffeine blocks the adenosine receptors and this makes the body less responsive to the build up of adenosine do reducing tiredness.
• alcohol initially acts as a depressant which can help us fall asleep more quickly. then it becomes a stimulant and therefore reduces the quality of sleep
• drowsiness is a major side effect of some anti-histamine medication. This is because histamine is a wakefulness neurotransmitter

Question 25

Caffeine and sleep - drake et al

• aim
• participants and method / procedure 
• Ivs
• results
• conclusion

Answer 25

Drake et al (2013)
- aim : effect of caffeine on sleep
- participants : 12 adult healthy men and women , all normal sleepers who were moderate consumers of caffeine.
Method : field experiment
Procedure : researchers tracked sleep by having participants keep sleep diaries and by using an at home sleep app. They were placed in 3 groups and given doses of caffeine in pill form at diffrent times. IV1 - at bedtime , IV2 - 3 hours before bed , IV3 - 6 hours before bed, IV4- no caffeine
Results / conclusion - caffeine has an effect on the total sleep time - group 1 with caffeine at bedtime got an average of 6.3 hours of sleep whilst group 4 no caffeine got 7.7 hours

Question 26

How does light affect sleep

- study supporting this

Answer 26

• artificial light and screens can affect release of melatonin
• SCN fails to keep track of day and night due to artificial light acting as zeitgebers , causing it to release melatonin at wrong time - or fail to release when it is time to sleep.
• change et al (2015) studies the bedtime use of tablets and E readers which emit light. They found that participants in their study released less melatonin , took longer to get get to sleep , had less REM sleep during the night and were less alert in the morning.

Question 27

How does Shift work affect sleep

Answer 27

• during a night shit an Individuals circadian rhythm is telling the body they should be sleeping but they have to stay awake. Then when trying to catch up on sleep during the day they may find it hard to fall asleep. The SCN takes time to adjust to changes in the Rhytm

Question 28

Czeizler et all - exposure to bright light during night shift work 
Aim 
Participants and method 
Procedure and IVS 
Results/ conclusion

Answer 28

Aim : to discover if exposure to bright light (zeitgeber) in the night shift workplace , and then total darkness at night for daytime sleep resets the circadian rhythm.
Participants : 8 men , 22-29 years old. Healthy. None had previous night work and none took alcohol or caffeine during the day. (Because alcohol / caffeine affects sleep) (drake et al and ebrahim found this)
Method: lab experiment
Procedure : 2 weeks study
Week 1 : no night shift but participants and body temp and saliva content of melatonin measured at different times day and night
Week 2: participants reported to lab at 9pm and finished work at 5am (morning)
IV1: participants worked in rooms lit by bright lights at the intensity of natural sunlight and then were given clear instructions for sleeping: to remain in complete darkness 9am to 5pm
IV2 : participants worked the night shift in rooms lit by ordinary lights and were given no clear sleep instructions.
DV: measurements to track participants circadian rhythm
:temp
Saliva to measure melatonin content
Urinary excretion rate
Score in alertness test
Score in mental maths test
Results
1) experimental group slept 2 hours more each day than control group
2)after 6 days experimental grouos found their CR completely flipped to suit night shift , control group showed little / no change. This was shown because melatonin concentration synchronised with the night work schedule , so they were similar to the previous daily CR of participants in the experimental group
3) scores in the alertness and mental maths tests in the experimental group were higher than the control group from midnight to 8am

Question 29

Conclusion and evaluation of czeisler et al (1990)

Answer 29

1) human cr can be adapted to shift work if treated with bright light at night and darkness in the day to sleep
2) shows bright light rested cr in 3 days - this is because bright light mimics the effect of daylight
Evaluation
3) night shift workers should have bright light to work in

Adv - lab exp meaning the study had high control As they were able to control extraneous variables. Te fact they were able to control the lights during the shift work and darkness during sleep, and give participants clear instructions allowed them to gain evidence for circadian rhythm adaptation. As well as this the study was highly beneficial due to the fact the results of the study can be applied to real life.
Dis- involved only few men , can’t be generalised onto others.
- nightshift work was stimulated in a lab, this may not have reflected real life working conditions , and would have low ecological validity - as all types of night shift work is different

Question 30

Figuero (impact of light from computer monitors on melatonin levels ) 
Aim 
Participants 
Method and procedure 
Result

Answer 30

Aim : to see the effect of computer monitor light on level of melatonin
Participants : 21 students from New York - all normal vision
Procedure : all used same make of iPad to play games , read , watch movies from 11 to 1am at night , all iPads turned to full brightness
IV1 : these participants wore blue light Goggles
IV2: these were orange tinted goggles
IV3 : these participants did not wear goggles
DV : melatonin concentration measured in the saliva of the participants collected at 1am
Results : after 2 hour exposure to light , there was suppression of levels of melatonin in saliva of partita onset in the clear goggled and blue light Google- but less suppression in orange goggle. Melatonin conc was 13pg/ml in blue light , but 31pg/ml in orange light

Question 31

Wiseman (2014)

Answer 31

Look at sleep and dreams booklet