Sleep & Dreams: Biological Approach Flashcards
1
Q
Role of the brain in sleep (8)
A
- Optic chiasm = x-shaped structure where the optic nerves cross
- Suprachiasmic nucleus (SCN) = small structure of the brain within the hypothalamus, located above the optic chiasm, responsible for regulating the production and release of melatonin
- Pineal gland = small endocrine gland that produces melatonin, which triggers sleep
- Melatonin = triggers wake and sleep phases and is the hormone produced when light levels fall, which increases the production of serotonin
- Adenosine = it builds up in the brain during the day, which makes us feel sleepy
- Glycogen = when we sleep, adenosine is cleared and is replaced by energy
- Serotonin = neurotransmitter (chemical) that collects in the hindbrain and reduces activity in the brain, triggering non-REM sleep
- Dark stimulates the process through the eye, onto the optic chiasm, then the SCN, then triggers the production of serotonin which triggers the pineal gland to produce melatonin, the sleep hormone
2
Q
Circadian rhythms (5)
A
- Internal body clock that controls when we are active and inactive
- Works over a period of 24 hours
- Is tied to sunlight
- Disrupting the rhythm of the body clock can lead to difficulties in sleeping, e.g. jet lag and shift work
- 1962 Michael Shiffre = spent two months underground and adapted to a 48-hour day and thought each 48-hour cycle was a regular day
3
Q
Non-REM and REM sleep and dreaming (4)
A
- REM = low voltage, mixed frequency, rapid eye movement, muscle atonia, most dreams take place here, paralysis, used to replenish and restore brain
- Slow-wave sleep (SWS) = restores the body, four stages of non-REM sleep, every six weeks half the brain tissue proteins are replaced, and anabolic function (normal bodily growth) takes place
- Sleep paralysis / sleepwalking takes place if there’s a glitch moving into REM sleep
- Temperature lowest at deepest stage of sleep
4
Q
Oswald’s Restoration Theory (8)
A
- 1966 and 1980
- Body and mind need rest period
- Tissue and nerve cells repair
- Anxiety levels are reduced
- Evidence in adaptation / evolution = animal sleep patterns reflect survival needs, conserve energy and sleep deprivation is harmful
- Sleep restores the body during inactive periods
- nREM (SWS) = restores the body’s biological processes that have become exhausted throughout active, waking hours; muscle tone decreases into SWS which conserves energy; allows the brain to relax; comes more at the start of sleep; need more SWS after intensive exercise
- REM = replenishes brain proteins and neurotransmitters, allows the brain to repair and reorganise, maintains brain activity during deep rest periods, body paralysis takes place to prevent injury, allows protein synthesis to take place and keeps brain alert during sleep hours
5
Q
Evidence for Oswald’s Restoration Theory (3)
A
- Shapiro et al, 1981 = measured sleep of ultramarathon runners after completing ultramarathons and for a few nights afterwards and found they had more SWS
- DJ Peter Tripp 1959 = broadcasted for 201 hours continuously, hallucinations started on day three, slept for 14 hours upon completion, unknown whether permanent effects as he said no but family and friends said yes
- Newborns can sleep up to 20 hours a day, usually over which 50% is REM, which is more than what adults have
6
Q
Aim and year of Dement and Kleitman study (2)
A
- 1957
- To determine when dreaming occurs during sleep
7
Q
Method of Dement and Kleitman study (6)
A
- Nine participants (seven male, two female)
- Reported to sleep lab before bedtime
- Avoided caffeine and alcohol that day
- Electrodes attached to head and around eyes to measure brainwaves and eye movement
- Woken by a bell during REM and SWS (either five or 15 minutes into REM)
- Reported what they were dreaming about (content and duration of dreams and emotions / feelings)
8
Q
Results of Dement and Kleitman study (6)
A
- Total of 351 awakenings
- REM dream recall = 152
- REM no dream recall = 39
- SWS dream recall = 11
- SWS no dream recall = 149
- Eye movement correlates with reported dream content
9
Q
Conclusion of Dement and Kleitman study (2)
A
- Aim was achieved
- Vast majority of dreams take place and are recalled during REM sleep as opposed to during SWS
10
Q
Dement and Kleitman follow-up studies (4)
A
- Correlation of REM sleep with dreaming substantiated
- Some evidence of being able to influence dreams with external stimuli, e.g. sound, light, cold water spray
- Individual differences in recalling dreams
- Nature of eye movement during REM less evident - people born blind and infants have movement patterns with no image basis
11
Q
Biological approach overview (7)
A
- Sleep and dreaming both linked to physiology
- Factors affecting sleep are linked to the medical (biological) approach, and these have a physical cause and can be treated
- Drugs and light are factors which affect sleep
- Sleep = a behaviour, an altered state of consciousness, the need to lie down for a few hours in a quiet and preferably dark environment, and a biological imperative
- We need sleep to function effectively
- We can adapt to some effects on sleep over a short period
- It’s difficult to resist pressure to sleep (we also use environmental cues)
12
Q
Sleep deprivation
A
- Obesity, coronary heart disease and diabetes can be consequences of sleep deprivation, according to NHS
- Reduces life expectancy
- Sleep deprivation changes your facial appearance (cues of fatigue)
- Sleep deprivation studies can be unethical
- 1983 and 1985 = rats used in extreme sleep deprivation studies, one rat survived for 32 days, all rats died, they were cold as couldn’t regulate body temperature, suffered ulcers to their paws and tails, and they were hungry and lost weight
13
Q
Onset of darkness …
A
… Triggers the process of falling asleep, but there are problems if light interferes - process stops when sleep hormones stop being released
14
Q
What happens during sleep? (2)
A
- Brain activity drops
- Heart rate slows
15
Q
Awake (2)
A
- Low voltage
- High frequency
