Sleep and circadian rhythms Flashcards
What is the study of sleep called?
Polysomnography
Name the three types of scans that are used in the study of sleep
EEG, EOG, EMG
Name the two types of brain activity waves during wakefulness, and name when they occur
Beta, during brain activity, and alpha, when the person is resting
What brain wave activity characterises stage 1 sleep?
Theta waves
What two features is stage 2 sleep characterised by?
Sleep spindles (rapid but short bursts of activity) and k complexes (high amplitude but slow)
Stage 3 sleep involves what brain waves?
Delta
What is another term for stage 3 sleep?
Deep sleep/slow wave sleep
What brain activity waves occur in REM sleep?
Beta and theta
How long does it take to cycle between all four stages and back?
90 mins
What was discovered by Dement and Kleitman in 1957?
Dreams
What % of dreams are 1. sad, angry or anxious, 2. happy, 3. of a sexual nature?
- 64%
- 18%
- 1%
What is Allan Hobsonsnactivation-synthesis hypothesis of dreaming?
The brainstem is activated during REM sleep and sends a signal to the cortex which creates images with actions and emotions from memory
There is no logic in dreaming however, when awake, the person tries to organise the content into a logical story
There is no meaning of dreams, however they are based on the persons experience
What is another name for Valli and Revonsuos coping hypothesis of dreaming?
The clinico-anatomical hypothesis
What does the clinico anatomical hypothesis/coping hypothesis of sleep suggest?
We dream about things we find threatening in our lives and dreams are biologically adaptive, tending to lead to enhanced coping strategies
What evidence supports the co-ping hypothesis of dreaming?
Problem solving occurs during sleep
What is the role of adenosine?
Accumalates during the day and promotes sleep, signals that there is very little energy and that we have used a lot of our energy already
Patients who had continuous sleep and would only wake up to eat and drink had damage to what brain area?
The base of the brain
Damage to what brain area is involved in insomnia patients?
Ventro-lateral preoptic area
What brain area is involved in wakefulness and who discovered the region?
The brain stem and Moruzzi and Mogoun, 1949
What is the name of the system operating during wakefulness?
Reticular activating system
What is the RAS
Composed of several nuclei that project to the forebrain and promote arousal
What are the different nuclei in the RAS
- Locus coeruleus
- Raphe nucleus
- Tuberomammillary nucleus
Nucleus basalis of Maynert
What did Ciff Saper term the battle between sleep and arousal?
The flip-flop switch
What peptide helps to maintain wakefulness?
Orexin/hypocretin
Endogenous cycles are generated based on what?
The earths rotation
What did Aschoff 1965 discover?
Humans placed in underground bunkers with no external cues showed daily sleep-activity rhythms, even though they drifted slightly above 24 hours
What are external cues called?
Zeitgebers
When a zeitgeber sets an internal rhythm it is said to be what?
Entrained
Travelling west does what to our circadian rhythm?
Phase-delays
What is the variability in our circadian rhythms called
Chronotypes
Where is the primary biological clock located?
SCN
What was discovered about neuronal activity in the the SCN during the light period?
More active
What happens following SCN transplantation?
The recipient follows the donors rhythm
How does light reach the SCN?
The retinohypothalamic tract
What is the special population of ganglion cells called that respond to light in the RHT?
Photo sensitive retinal ganglion cells
What is the special pigment found in PRGCs?
Melanopsin
What initiates the transcription of the PER and TIM genes?
The clock and the activators
In drosophila, what two genes are activated that produce proteins? and what proteins do they produce?
Per gene and tim gene, producing PER and TIM
What does it mean to form dimers?
The two proteins pair up
What do the dimers do once they are paired?
They translocate to the nucleus and inhibit the transcription of more of themselves
In mammals what are the names of the genes and the proteins they create?
CLOCK and BMAL1 gene, creating per 1,2,3 of cryptocome 1,2 which produced cry
High amounts of inhibition = high amounts of proteins in the nucleus = what?
Sleepiness
What other glands does the SCN control during wake and sleep?
The pituitary gland ~(light phase) and the pineal gland (dark phase)
How does melatonin affect breeding?
More melatonin produced in winter shrinks the gonads
How does the circadian rhythm affect treatment of disease?
- Drug toxicity varies from 20-80% depending on time of day
- Risk for illness also changes, with a higher likelihood of stroke and heart attacks in the morning due to a surge in cortisol
Name the four reasons why we sleep?
- Adaptive
- Restorative
- Promotes development
- Facilitates cognition
What is removed from the body during sleep that promotes restoration?
Free radicals and toxic waste
When is growth hormone at its peak?
During REM sleep
LC = ?
RN = ?
TMN = ?
NBM = ?
1.Norepinephrine/noradrenaline
2. 5-HT
3. Histamine
4. Acetylcholine
What is secondary insomnia?
Inability to sleep due to another mental or physical condition
Give an example of a pharmacological hypnotic
GABA-a agonists, BZDs and antihistamines
Name three sleep disorders that is not insomnia
- Narcolepsy
- Sleep apnea
- REM sleep disorder behaviour
Name the three main symptoms of narcolepsy
Sleep attacks, cataplexy, sleep paralysis
What occurs in REM sleep disorder?
The behaviour of people corresponds with the contents of their dreams
What problems can low-wave sleep cause?
Bed-wetting, sleepwalking and night terrors
