EEG, SLeep and Circadian Rhythms

Question 1

What is sleep?

Answer 1

State of unconsciousness from which individual can be aroused by normal stimuli, light, touch, sound etc. Predictable and Cyclical

Question 2

Why is sleep important

Answer 2

Range of functions, including:
-Reduced general metabolism
-Clearing out from CNS
- Neuronal plasticity
-Sorting of memories (Learning and memory)
-Cognition
–Immune function

Question 3

Where does sleep originate from in the brain?

Answer 3

Pons and below

Question 4

What 2 centers exist in the reticular formation and how do they control our sleepiness?

Answer 4

Awake (arousal) and Sleep centrers,

Awake (Orexin) stimulates wakefulness, whilst the sleepy one stimulates sleep. They wake up and overtake the other when it comes to bed time or waking up.

Question 5

How do:
Adenosine
Delta Sleep inducing peptides (DSIPS)
melatonin
serotonin

contribute to sleep?

Answer 5

Adenosine - levels increase throughout the day, at threshold sends us to sleep. Adenosine receptors are antagonised by caffeine -> keeps us awake.

Delta Sleep inducing peptides (DSIPS) - induce sleep (duh)

melatonin - darkness causes its production by the pineal gland. In humans and other non nocturnal animals it sends us to sleep.

serotonin - related to melatonin. Potentially a precursor.

Question 6

Where is the suprachiasmatic nucleus? How does what does it do?

Answer 6

In the hypothalamus

Involved in circadian rhythm and production of melatonin. (removes inhibition of melatonin production when darkness falls)

Question 7

How does light affect the laevel of melatonin?

Answer 7

Light causes inhibition opf melanin production

Question 8

What is Orexin?Defective Orexin signalling causes what disease?

Answer 8

Melatonin inhibits orexin (Hypocretin) - excititory neurotransmittor released from hypothalamus. - awake and aroused hormone.

If defective, known as narcolepsy (can spontanwously fall asleep

Question 9

What does frequency of brainwaves determine, go from long waves to short waves

Answer 9

State of conciousness

So the longer the wave, the more asleep we are.

Long: anasthesia - sleep - relaxed awake - focussed awake - Tonic-clonic Epilepsy = Short

Question 10

Increased amplitude (on EEG) means what i terms of neuranoal concentration

Answer 10

The higher the deeper the sleep

(because the more brain activity, the more crosswaves etc and so the more some of the height has been cancelled out etc)

Question 11

Alpha waves
Beta waves
Theta waves
Delta

wave patterns mean what state of alertness?

Answer 11

Alpha waves - A for Awake but relaxed. (imagine A as one wave) high frequency and mid amplitude

Beta waves - B for Buzzing (imagine B as waves, fits 2 in the same amount of space as A) very high frequency, low amplitude

Theta waves - Mum asleep at the Theatre (early stages of sleep) - long waves and varying amplitude

Delta waves - The BIG BOYS - D for the DEEPEST sleep you ever had which was on Delta airlines. Biggest amplitude and lowest frequency.

Question 12

Why low B waves amplitude but alert and awake state?

Answer 12

Because so much activity with waves in all directions that some of the waves cancel each other out. (asynchronous activity)

Question 13

5 stages of sleep - what are they and what waves do they have

Answer 13

1 - light sleep. Slow eye movements (NON REM) -> Theta (high amp, low frequency)

2 - mid sleep. Eye movements stop. Has “Sleep Spindles” -> Theta (but slower frequency)

3 - deep sleep (part 1) -Delta (high amplitude and very slow, decreasing spindle activity)

4 - deepest sleep - exclusively Delta

(5) - REM sleep - Looks like awake on graph

Pattern goes something like 1,2,3,4,3,2,REM, 2,3,4,3,2,REM,2,3,2,REM,2,3,2,REM

Question 14

When do we usually go into deep sleep?

Answer 14

earliest part of the night a couple of times

Question 15

What happens in deep sleep?

Answer 15

Body relaxes (reduced vascular tone (and therefore BP)), reduced metabolic rate (and so decreased body temp), and resp rate

V active hippocampus

Question 16

physiological appearances of REM sleep, and when does it happen?

Answer 16

Later on in the night, 5-30 mins at a time.

Brain very active, firing as if it is highly alert and awake. DREAMS. Eye muscles - bursts of rapid activity.

Question 17

REM Sleep Behavioural Disorders what happens?

Answer 17

Lacking the inhibitory projections from the pons to the spinal chord, so when in REM sleep will act out dreams.

Question 18

Where i the inhibition occuring in REM Sleep to prevent acting out dreams?

Answer 18

Between the pons and the spinal chord

Question 19

What pathway is REM sleep dependant of?

Answer 19

Cholinergic pathways in the reticular formation (so anticholinesterases increase the time spent in REM sleep)

Question 20

What happens if you are deprived in REM sleep

Answer 20

You will catch up on subsequent nights

Question 21

What happens to our REM sleep as we get older?

Answer 21

It decreases, possibly due to cognitive decline. As it is associated with maybe making new neuronal connections it could mean that less new neuronal connections are being made

Question 22

What is insomnia?

Answer 22

chronic inability to obtain the necessary amount or quality of sleep to maintain adequate daytime behaviour”, very subjective, very common.

Question 23

primary vs secondary insomnia

Answer 23

Primary is chronic - no identifiable cause

Secondary = temporary due to pain, bereavement or other crisis, usually short lived.

Question 24

How to treat insomina?

Answer 24

Usually nowadays with proper sleep hygiene! (no eating, exercise or screen/visual stimulus before bed)

Question 25

Nightmares vs Night Terors?
What is Somnambulism?

Answer 25

Nightmares are just bad dreams. REM sleep.

Night terrors = delta, deep sleep. Usually 3-8 year olds, early in night. include physical reactions such as shaking, thashing and screaming and even though eyes open won’t necessarily recognise parents.

Somnambulism = sleep walking, often stage 4 sleep. Appear awake and often obey instructions

Question 26

Wha thappens in NArcolepsy

Answer 26

dysfunctional orexin release (from hypothalamus), so can sokmetimes spontaneously fall asleep (straight into REM sleep)