Sleep

Question 1

How many hours of sleep are needed for different stages in a human’s life?

Answer 1

16 hours for, 9 for teenagers, 7-8 for adults

Question 2

Is there any adaptations for sleep deprivation?

Answer 2

No, when sleep is missed it is not made up

Question 3

Describe stage 1, 2, 3, 4 and REM sleep

Answer 3

Stage 1 - intermediate stage between waking and sleeping, theta activity
Stage 2 - shows sleep spindle and K complexes
Stage 3 & 4 - Begin slow wave sleep with delta activity
REM sleep - most like waking with theta and beta activity

Question 4

What are the differences between Slow Wave Sleep (SWS) and Rapid Eye Movement sleep (REM)?

Answer 4

REM - characterised by EEG desynchrony, lack of muscle tone (paralysis) and rapid eye movement
SWS - EEG synchrony, moderate muscle tone and absence of eye movement

Question 5

What is insomnia and how is it treated?

Answer 5

Affects 25% of the population, reducing quality of sleep. People often report less sleep than they actually get.
Pharmacological treatments try to treat quality of sleep

Question 6

What is sleep apnea?

Answer 6

Condition where breathing ceases during sleep

Question 7

What is narcolepsy?

Answer 7

A sleep disorder whose primary symptom is a ‘sleep attack’, where patient suddenly falls asleep

Question 8

What is cataplexy?

Answer 8

Where, in response to high excitement, sleep attack is provoked where eyes are open and consciousness is maintained but muscle tone is lost

Question 9

What is sleep paralysis?

Answer 9

Condition where paralysis is present after waking with hypnagogic hallucinations, belived to be a result of REM dreaming and paralysis not being turned off

Question 10

How is narcolepsy usually treated

Answer 10

With modafinil

Question 11

What is REM sleep disorder and what is it believed to be caused by?

Answer 11

• Lack of REM paralysis causes people to act out their dreams
• Believed to be due to accumulation of alpha synuclein in neurons that can be treated with benzodiazepine

Question 12

Name 3 slow wave sleeping disorders associated with childhood

Answer 12

Sleep walking, bed wetting and night terrors

Question 13

What 3 types of neurone are active during waking and inactive during sleep?

Answer 13

1. Noradrenaline
2. Serotonin
3. Orexinergic

Question 14

What area was described by von Economo as producing encephalitis lethargia when damaged?

Answer 14

Preoptic area of the hypothalamus, with the key area being the ventrolateral preoptic area (vlPA)

• Damage to area produces insomnia in rats
• Stimulation induces sleep

Question 15

What 3 systems are believed to interact to produce arousal and sleep?

Answer 15

• Mutual inhibition between sleep promoting areas on vlPA and Brain stem/forebrain arousal systems
• Orexinergic neurones in lateral hypothalamus activate brain stem/forebrain maintaining switch ‘on’

Question 16

Name 2 things that affect orexinergic neuron activity

Answer 16

1. Levels of adenosine which builds up during prolonged awakeness (blocked by caffeine)
2. Hunger and satiety levels

Question 17

What abilities are affected during sleep deprivation?

Answer 17

cognitive abilities such as speech production, focusing abilities are impaired (not as much movement impairment)

Question 18

Which neurons switch REM sleep on and off?

Answer 18

‘on’ switch - acetylcholine cells found in sublateraldorsal nucleus (SLD) in the dorsal pons
‘off’ switch - ventrolateral periaqueductal grey matter (vlPAG) which receive input from arousal systems to keep them active

Question 19

What effects were observed in sleep deprived rats?

Answer 19

1. Increased metabolic rate and weight loss despite increased food intake
2. Inability to thermoregulate
3. Death after 2-3 weeks

Question 20

What are the proposed functions of SWS?

Answer 20

• Reduced metabolic rate and blood flow to provide body with rest
• Regions most active during waking have lowest metabolic activity during SWS
• Could protect from free radicals and oxidative stress in the cortex

Question 21

How does sleep protect the brain?

Answer 21

• cerebrospinal fluid (CSF) penetrates much further into the brain during sleep
• toxic chemicals such as amyloid are removed more quickly during sleep

Question 22

What is the proposed function of REM sleep?

Answer 22

Reinforcing declarative/non-declarative memory

• People do better in tasks after taking nap with REM
• Place cell sequence replayed during rat sleep, could be consolidating memory

Question 23

What are the 4 biological rhythms and their time periods?

Answer 23

Ultradian - multiple within 24 hours
Circadian - 24 hours
Infradian - Longer than 24 hours
Circannual - Year long cycle

Question 24

Which regions of the brain control circadian rhythms?

Answer 24

Lesions to suprachiasmatic nucleus (SCN) disrupts sleep timings.

• Receives input from the retina via light-sensitive ganglion cells
• Region projects indirectly to the VLPA and orexin neurons in the lateral hypothalamus

Question 25

What proteins control biological rhythms?

Answer 25

7 different proteins such as period (per), cryptochrome (cry) and clock, pulses of light can reset these levels

Question 26

How does the pinneal gland control seasonal cycles?

Answer 26

By secreting melatonin at night