P6: Sleep

Question 1

What does the article of Lieblau say about the causes of Narcolepsy?

Answer 1

The sleep disorder narcolepsy is linked to immune-system genes and is caused
by the loss of neurons that express the protein hypocretin. Hypocretin-targeting
immune cells could be the cause and have now been found in people with narcolepsy.
If further experiments strengthen the proposed link between increased T­cell
reactivity to hypocretin and neuronal damage targeted immune therapies could be developed and used to target the immune system at the onset of narcolepsy.

Question 2

What are specific criteria of phase 1?

Answer 2

N1: alphawaves – 8-12 per second. Vertex spikes
between sleep and wakefulness: some theta waves, hallucinations and hypnagogic illusions
Feeling of falling  muscle twitches

Question 3

What are specific criteria of sleep phase 2?

Answer 3

N2: 12-14 waves per second.
slightly deeper state of sleep. More theta waves.
Sleep spindles: fast frequency, low amplitude. bursts of rapid rhythmic brain activity. k-complexes: lower frequency and bigger amplitude. suppress cortical arousal and keep you sleeping  transferring memory into LT-memory. If you gently touch someone they will have k-complexes to suppress the processing because the touch is non-threateningkeeps you asleep

Question 4

What are specific criteria of sleep phase 3?

Answer 4

N3: slow wave sleep: delta waves. Difficult to wake up. Widespread synchronization of cortical activity. Large amplitude and very slow waves.

Question 5

What are specific criteria of sleep phase 4?

Answer 5

N4: REM sleep: rapid eye movement: muscles are paralyzed. So your muscles are not moving. Brain seems very awake but prevents your body from doing anything. EEG activity resembles that of waking.
Brainstem regions are inhibiting motor neurons.

Question 6

What is the sequence when we fall asleep to move to REM?

Answer 6

N1->N2->N3->N2->N4

Question 7

How does the Circadian rhythm work?

Answer 7

Input: light eye. Melanopsin detectors  release Glutamate in the SCN(excitatory) SCN: suprachiasmatic nuclei in the hypothalamus which is closely linked to the pineal gland: it releases Melatonin which builds up over the day and makes you slightly sleepy optimally 2 hours before you go to bed. SCN is the master clock.

Question 8

What is involved in the sleep wake flip flop switch?

Answer 8

awake signal: lateral hypothalamus: histamine(TMN) and orexin: by hypocretin neurons.
awake signal: brainstem: Locus coeruleus(LC): noradrenaline + raphe nuclei(RN): serotonin

sleep signal: Ventrolateral Preoptic Nucleus(VLPO)(hypothalamus) –> releases GABA and is connected to the other nuclei –> inhibitory

However, not only is VLPO able to inhibit TMN, LC, RN and others, but they can also inhibit VLPO – and together they make the two poles of our flip-flop switch.

In the prolonged state of arousal, certain chemicals (such as adenosine) build up in the brain and tend to shift the balance to the sleep state.
–> Thats why coffeine which is an adenosine antagonist makes us feel awake