sleep

suprachiasmatic nucleus (SCN)

biological clock regulating circadian rhythms

reticular activating system

maintains wakefulness via acetylcholine, norepinephrine, serotonin and histamine

vLPOA

inhibits wakefulness promoting regions to induce sleep

lateral hypothalamus

releases orexin to stabilise for wakefulness

orexin (hypocretin)

a neuropeptide in the hypothalamus which plays a key role in maintaining wakefulness and preventing narcolepsy

sublaterodorsal nucleus (SLD)

controls REM sleep and muscle paralysis

magnocellular nucleus

inhibits motor neurons during REM to prevent movement

what waves charcterise stage 1 of NREM sleep

theta waves

what characterises stage 2 of NREM sleep

k-complexes and sleep spindles which stabilise sleep

what waves charcterise stage 3 and 4 in NREM

delta waves which are important for brain recovery

PGO waves

eletrical bursts of activity which propogate to the lateral geniculate nucleus and occipital cortex, relevant for maintaining and the onset of REM sleep

PGO and REM

linked to visual dreams in REM

k-complexes

brainwave spikes to suppress arousal and keep us asleep

sleep spindles

bursts of brain activity to portect sleep and aid memory formation

adenosine

sleep molecule which builds when youre awake to make you sleepy, is targeted by caffeine

allostatic regulation

overrrides homeostatic sleep drive in emergencies such as hunger or stress

hypocretinergic neurons

brain cells tgat produce and release orexi

lack of orexin/ hypocretinergic neurons

narcolepsy

pineal gland and melatonin

releases melatonin in response to darkness, promoting sleepiness in regulation of the sleep-wake cycle and circadian rhythms

7 excitatory factors which promote wakefulness and arousal

1. acetylcholine

2. norepinephrine

3. serotonin

4. histamine

5. orexin

6. cortisol

7. ghrelin

what promotes cortical activation

acetylcholine

where is norepinephrine released from

locus coeruleus

where is serotonin released

raphe nucle

where is histamine released

tuberomammillary nucleus

ghrelin

hunger hormone that stimulates wakefulness to promote food-seeking behaviour

4 inhibitpry factors which promote sleep

1. adenosine

2. GABA

3. melatonin

4. leptin

leptin

relax hormone which inhibits hypocretinergic neurons to promote sleep

sleep apnoea

breathing interruptions during sleep which reduces overall quality and recovery processes

narcolepsy

sudden sleep attacks, cataplexy, sleep paralysis, and hypnagogic hallucinations

cataplexy

loss of muscle tone without loss of consciousness

what is narcolepsy caused by

an orexin deficiency

REM sleep behaviour disorder (RBD)

lackof muscle paralysis during REM

what might RBD be linked to

damage to the magnocellular nucleus

activation synthesis hypothesis

psotits dreams are a result of the brain trying to make sense of random neuronal activity during REM

hypnagogic hallcuinations

hallucinations that occur when going to sleep ; seen in narcolepsy

flip-flop

SLD and VLPAG regulate sleep-wake REM transitions by mutually inhibiting each other - when one is active, the other is suppressed

SLD and REM

The SLD promotes REM sleep by activating REM-specific muscle atonia and cortical activity

VLPAG and REM

The vlPAG suppresses REM sleep by inhibiting REM-promoting neurons in the SLD