9: Sleep

Question 1

Experimental sleep-loss paradigms:

Answer 1

• Acute sleep deprivation (SD): full one-time absence of sleep -> Sleep homeostasis
• Chronic sleep restriction (SR): repeat. reduced time (1-2 weeks) -> closer to reality

Question 2

Sleep restriction and risk taking:

Answer 2

• Sleep restriction over longer period -> more risk taking
• One time sleep deprivation no effect

Question 3

Experimental manipulation of slow waves:

Answer 3

„Closed-loop“ auditory stimulation -> tone in synchrony with slow waves
-> increases slow wave activity -> deeper sleep
-> 20% more slow wave
-> Clinical application?

Question 4

Sleep-wake disturbances in Parkinson’s disease

Answer 4

• Insomnia ~ 80-90% of patients
• Sodium Oxybate -> produces slow wave sleep ->better deep sleep ->less daysleepiness
• Problem: strong medicine, addictive
• No Changes in Subjective Sleep Quality and Sleepiness after Short-Term Application
• But: 2 Weeks of Auditory Stimulation Improve Subjective Sleepiness and Wellbeing
• -> potential neuroprotective role of deep sleep: modulation of disease progression -> more deep sleep -> slower PD progression
• Deep sleep decreases, fragmented sleep increases α-Synuclein deposition

Question 5

Effects of sleep on neurodegeneration: Alzheimer’s disease (AD):

Answer 5

Sleep restriction accelerates & sleep enhancement decelerates beta-amyloid deposition

Question 6

2-process model of sleep regulation:

Answer 6

• Homeöostasis: je länger wach, desto stärkeres Schlafbedürfnis
• Zirkadianer Prozess: innere Uhr beeinflusst Schlafbedürfnis

Question 7

Polysomnography: EEG, EOG, EMG

Answer 7

• normal: 4-5 cycles per night, immer mehr REM, immer weniger deep sleep
• Bei Parkinson/Depression ganz andere Rhythmen

Question 8

Vigilance Test:

Answer 8

• MSLT: Multipler Schlaflatenz Test -> versuchen einzuschlafen
• MWT: Multipler Wachhalte Test -> versuchen wach zu bleiben

Question 9

Neurological Sleep-Wake Disorders:

Answer 9

• Insomnia
• Hypersomnia
• Parasomnia (disorders of arousal) (Schlafwandel)
• Circadian sleep-wake disorders (delayed rhythm, shorter/longer)
• Sleep-related movement disorders (urge to move during night)
• Sleep-related breathing disorders (eg. obese people)
• Isolated symptoms

Question 10

Hypersomnia

Answer 10

Chronic excessive daytime sleepiness

Clinical characteristics:
- Cataplexy (muscle tone loss with consciousness, upon strong emotions, few seconds up to min)
- Hypnagogic (upon falling asleep) or hypnopompic (upon awakening) hallucinations
- Sleep paralysis
- Fragmented night sleep

Etiology:
- Loss of wake-promoting hypothalamic orexin / hypocretin neurons (autoimmune cause?) -> REM not working -> no movement possible

Diagnosis:
- Actigraphy: regular daytime naps, fragmented night sleep
- Polysomnography: short sleep and REM sleep latencies, increased numbers of arousals
- Multiple sleep latency test: short mean sleep latency, multiple sleep-onset REM periods
- Cerebrospinal fluid: decreased orexin levels

Treatment:
- Sleep hygiene
- Stimulants (z.B. Modafinil, Methylphenidate)
- Sodium-Oxybate (nocturnal application)

Question 11

Insomnia

Answer 11

• Chronic problems with falling asleep and/or sleeping through
• not caused by external factors like noise
• negative daytime consequences -> fatigue, sleepiness, irritability, mood swifts, cognitive deficits,…

Causes:
- Stress as trigger -> psychophysiological insomnia
- With psychiatric comorbidities
- With system diseases
- Primary (rare)

Diagnosis:
• History-taking!
• Sleep lab examinations mostly useless
• Look for potential causes underlying secondary insomnia

Treatment:
- Sleeping pills (benzodiazepines) only for short-term use! (days up to 1-2 weeks)
- cognitive behavioral therapy (CBT)
- Sedating antidepressants

Question 12

Parasomnia

Answer 12

NREM Parasomnias
• Somnambulism: Schlafwandel
• Confusional arousal
• Sleep terror / Pavor nocturnus
-> Frequent in children, less in adults

Treatment:
- Avoid provocation factors (like sleep deprivation)
- Protective measures against injuries
- Weak evidence for drugs: benzodiazepines, antidepressants

REM sleep behavior disorder:
- Acting out dreams (vocalizations, movements, sometimes with injuries to bedpartners)
- Often associated with memories of frightening dreams
- In second half of night

Clinical significance:
• Heralds neurodegenerative disease (alpha-synucleinopathies)-> high risk for PD!

Treatment:
Clonazepam, melatonine

Question 13

Circadian disorders:

Answer 13

Example: free-running type
Manifestation: >24 hour rhythm -> daily backwards shift of sleep times

Cause: Unknown -> more often in blind people

Diagnosis: Actigraphy over 2-3 weeks, Melatonine profiles

Treatment: Difficult (melatonine in evening hours, light therapy in morning hours)

Question 14

Sleep-related movement disorder:

Answer 14

Example: Restless legs syndrome
Clinics: urge to move legs, unpleasant feeling, improves with movement, predominant at night, during rest periods

Epidemiology: frequent (5-10%)

Cause: idiopathic form: unknown (iron? dopamine?)
secondary forms: e.g. uremia, polyneuropathia…

Diagnosis: History-taking, examination, Dopamination treatment, Polysomnography

Treatment: First choice: Dopaminergics, gabapentine / Second choices: hypnotics, other antiepileptics, opioids