Sleep

Question 1

What is sleep? What does it involve?

Answer 1

• Stereotypic or species-specific posture
• Minimal movement
• Reduced responsiveness to external stimuli
• Reversible with stimulation – unlike coma, anaesthesia or death

Question 2

What measurements are used to evaluate sleep / sleep patterns?

Answer 2

EEG (brain waves)
EOG (eye movements)
EMG (muscle movements -> jaw)

Question 3

What are the stages of sleep?

Answer 3

• awake
• Stage 1&2 (NREM)
• Stage 3&4 (NREM)
• Stage 5 (REM)

Question 4

What does REM stand for?

Answer 4

Rapid Eye Movement

Question 5

What is a common characteristic of stage 2 sleep on the EEG?

Answer 5

sleep spindle

Question 6

How is sleep structured?

Answer 6

• divided into 5 stages

- multiple sleep cycles

Question 7

When are you most likely to dream?

Answer 7

• during REM sleep but not exclusively

Question 8

What are lucid dreams?

Answer 8

In the dream you are aware that you are dreaming

Question 9

How is sleep controlled?

Answer 9

• the RAS is important for enabling conciousness
• Lateral hypothalamus: promotes wakefulness, suppresses RAS
• ventrolateral preoptic nucleus: promotes sleep, suppresses RAS

Question 10

RAS

Answer 10

• Reticular activating system
• projections from brainstem to thalamus and cortex
• it is not the center of conciseness. It enables conciseness, without it consciousness would not be possible.
• > stimulated by lateral hypothalamus
• > suppressed by ventrolateral preoptic nucleus.

Question 11

What do different sleep phases look like on EEG, EMG, EOG?

Answer 11

• rapid eye movement in Stage 5, looks like in awake
• higher heart rate and breathing rate in REM
• overall slowing EEG in the sleep stages until REM sleep is reached and increased EEG speed

Question 12

SCN

Answer 12

= suprachiasmatic nucleus

• tracks level of ambient light (“clock”)
• has connections to LH, VLP, RAS and the pineal gland (melatonin release)
• synchronises sleep with falling light level
• regulates the circadian rhythm

Question 13

Pineal gland

Answer 13

• responsible for melatonin release

- stimulated by the SCN

Question 14

Lateral Hypothalamus

Answer 14

• promotes wakefulness (orexin, hypocretin)

Question 15

Ventrolateral preoptic Nucleus

Answer 15

• (in anterior hypothalamus)

- promotes sleep

Question 16

What are indices that sleep is necessary?

Answer 16

• Most/all animals sleep
• Sleep deprivation is detrimental
• Sleep is regulated accurately

Question 17

What are the psychiatric and neurological consequences of sleep deprivation?

Answer 17

– Sleepiness

• irritability
• stress
• mood fluctuations
• depression
• impulsivity
• hallucinations
• psychosis
• seizures (especially in epilepsy but also in healthy poeple)

Question 18

What are the neurological consequences of sleep deprivation?

Answer 18

– Impaired attention, memory, executive function
– Risk of errors and accidents (e.g. shift work, doctors)
– Neurodegeneration (?)

Question 19

What are the somatic complications of sleep deprivation?

Answer 19

– Glucose intolerance
– Reduced leptin/increased appetite
– Impaired immunity
– Increased risk of cardiovascular disease and cancer 
– Death

Question 20

What is sleep important for?

Answer 20

• normal brain funciton
• memory consolidation
• e.g. affected brain activation when solving math problems in a sleep deprived state.

Question 21

How is sleep regulated? I.e. what happens after sleep deprivation?

Answer 21

After sleep loss:
• Reduced latency to sleep onset
• Increase of slow wave sleep (NREM)
• Increase of REM sleep (after selective REM sleep deprivation)

Question 22

What are the functions of sleep?

Answer 22

• Restoration and recovery – but active individuals do not sleep more
• Energy conservation – 10% drop in BMR – but lying still is just as effective
• Predator avoidance – but why is sleep so complex?
• Specific brain functions – memory consolidation, …

Question 23

What are dreams? When do they occur?

Answer 23

• Can occur in REM and NREM sleep
• Most frequent in REM sleep
• More easily recalled in REM sleep
• Contents of dreams are more emotional than ‘real life’
• Brain activity in limbic system higher than in frontal lobe during dreams

Question 24

What is the function of dreams?

Answer 24

• Safety valve for antisocial emotions
• Disposal of unwanted memories
• Memory consolidation

(Freud? - dealing with problems, anxiety)

Question 25

Insomnia

Answer 25

• High prevalence

* Most cases transient

Question 26

Causes of chronic cases of Insomnia?

Answer 26

– physiological e.g. sleep apnea, chronic pain
– Brain dysfunction eg. depression, fatal familial insomnia, night working
- Anxiety and other psychological issues?

Question 27

How do you treat insomnia?

Answer 27

– sleep hygiene
– hypnotics (most enhance GABAergic circuits)
– sleep CBT
- medications - now GPs are more careful when prescribing these.

Question 28

Obstructive sleep aponoea

Answer 28

• people feel tired during the day
• they usually don’t remember waking up at night
• very common cause of Insomnia
• interrupted sleep

Question 29

Improving sleep quality - sleep hygiene

Answer 29

• establishing fixed times for going to bed/waking up
• creating a relaxing bedtime routine
• only going to bed when you feel tired
• maintaining a comfortable sleeping environment
• not napping during the day
• avoiding caffeine, nicotine and alcohol late at night
• avoiding eating a heavy meal late at night
• don’t use back-lit devices shortly before going to bed

Question 30

Hypersomnia

Answer 30

excessive daytime sleepiness or excessive time spent sleeping, is a condition in which a person has trouble staying awake during the day.

Question 31

What are some common and some primary causes of Hypersomnia?

Answer 31

Primary: Narcolepsy, post traumatic brain injury, idiopathic hypersomnolescence

Common:

• obstructive sleep apnoea
• restless leg syndrome
• nocturnal pain
• neurodegenerative disease
• medication
• environmental factors such as noise
• anxiety
• oesophageal acid reflux
• severe bruxism

Question 32

What is a subjective test to assess sleepiness?

Answer 32

The Epworth Sleepiness Scale

rate the likelihood of dozing in the following situations

Question 33

Epworth Scale

Answer 33

• Epworth Sleepiness Scale -> likelihood of falling asleep in certain sitations
• likelyhood between 0-3
• scala goes up to 24 points

Question 34

Narcolepsy

Answer 34

• Falling asleep repeatedly during the day and disturbed sleep during the night
• Cataplexy (sudden, brief loss of voluntary muscle tone, often triggered by strong emotions e.g. laughter)
• Dysfunction of control of REM sleep
• Orexin/hypocretin deficiency

Question 35

Cataplexy

Answer 35

sudden, brief loss of voluntary muscle tone, often triggered by strong emotions e.g. laughter

Question 36

Effects of shift work on sleep

Answer 36

• Night working causes physiological processes to become desynchronised
• This can lead to sleep disorders, fatigue and an increased risk for some conditions such as obesity, diabetes and cancer

Question 37

Sleep and Neurodegenerative disease

Answer 37

• cause or consequence?

- sometimes sleep issues happen before but it could also be an early manifestation of dementia

Question 38

Lewy-Body dementia

Answer 38

often preceded by REM problems (e.g. hitting, shouting, falling out of bed during sleep)