Module 8: Sleep and Dreaming Flashcards
1
Q
Explain NREM sleep
A
- Stage 1: light sleep, easily woken, alpha/theta brainwaves, eye movements slow
- Stage 2: late night, brain activity bursts (spindles), body temperature drops, heart rate slows, eye movements stop
- Stage 3: transition between 2 and 4
- Stage 4: deep sleep, slow delta waves, hard to wake, sleepwalking/nightmares in children
2
Q
Explain REM sleep
A
- Rapid eye movement
- Dreaming - 2hrs per night
- Sensory blockade
- Movement inhibition (spinal cord neurons turned off by pons)
- Heart rate/blood pressure rises
3
Q
Explain the sleep cycle
A
- Five cycles (1 = 90mins)
- Deep sleep and little REM –> light sleep and long REM (up to an hour)
4
Q
What are the functions and benefits of sleep?
A
- Deep sleep stops after age ~65
- Sleep needed for learning and survival
- 20% of sleep is REM, 50% for babies
- Dreaming can occur in NREM
- Adults need 7-8hrs, teens need 9hrs
5
Q
Explain circadian rhythms
A
- Controlled by suprachiasmatic nuclei (SCN) which is set by external triggers
- 24 hour cycle (sleep/wake, body temperature)
6
Q
Explain zeitgebers as an external influence on sleep
A
- Environmental cues (light/dark cycle, seasons, hunger)
- Entrainment - biological rhythms being matched to external triggers
7
Q
What are the strengths and weaknesses of zeitgebers as an external influence on sleep?
A
- Strengths: Practical applications (aid shift workers), Mistlberger & Skene (2004) found light a strong influence on sleep
- Weaknesses: Differing findings (Siffre 1975), studies usually unnatural
8
Q
Explain ultradian rhythms
A
- Less than 24 hours
- Sleep/REM cycle, heart rate, hunger, etc
9
Q
Explain internal influences on sleep
A
- Biological clock internal, keeps all rhythms synchronised
- Hormones: adrenaline/cortisol affect sleep, sleep resets hormones
- Melatonin signals need to sleep, released by pineal gland (trigger by darkness)
- Melatonin works as medication for insomnia/jet-lag (not shift workers)
10
Q
What are the strengths of internal influences on sleep?
A
- Evidence from animal studies
- Miles et al (1977) human study on blind person
- Li-You Chan et al. (2015) evidence for melatonin
11
Q
What are the weaknesses of internal influences on sleep?
A
- Cannot always generalise animals studies to humans
- Evidence relating to blindness is weak
12
Q
What are the symptoms of insomnia?
A
- Difficulty falling asleep
- Waking a lot in the night
- Not feeling refreshed waking up
- Feeling stressed/irritable
- Acute/chronic, 1 in 3 people, more common in older people
13
Q
Give explanations for insomnia
A
- Jet lag/night shifts
- Health conditions (physical/mental)
- Medication, food, drink (hormones affected)
14
Q
What are the symptoms of narcolepsy?
A
- No control over sleep/wake cycle
- EDS (excessive daytime sleepiness)
- Hallucinations and vivid dreams
- Cataplexy in 70% - loss of muscle power/tone due to onset of strong emotions (e.g laughter)
- Sleep paralysis and abnormal REM
- Affects 1 in 2000 people
15
Q
Give explanations for narcolepsy
A
- Lack of hypocretin
- May be genetic
- Stress/trauma
- May have evolutionary benefit (play dead)