Chronobiology

Question 1

Part of the brain regulating REM

Answer 1

-Pons

Question 2

Stage 1 sleep

Answer 2

• Light sleep or NREM

- High frequency, low voltage theta waves

Question 3

Stage 0 sleep

Answer 3

• Drousy
• Alpha waves
• Beta waves (when more excited)

Question 4

Stage 2 sleep

Answer 4

-Start to see K complexes and sleep spindles

Question 5

Stage 3 sleep

Answer 5

-Start to see delta waves

Question 6

Stage 4 sleep

Answer 6

• Delta waves are greater than 50%
• Parasympathetic control
• Lowered vital signs
• Restorative, deepest sleep

Question 7

REM

Answer 7

• Sawtooth waves
• Desynchronized, paradoxical, activated
• Low voltage, high frequency with random fast sawtooth waves
• Paralysis occurs
• Dreams occur
• Eyes move and erections occur
• Sympathetic tone dominates
• Likely controlled by LDT/PPT ACh firing
• Atonia: GABA and glycine released into spinal motor neuron tracts

Question 8

Reticular formation

Answer 8

-Main system that keeps you awake

Question 9

6 transmitters that keep you awake

Answer 9

• ACh
• Glutamine
• Norepi
• Dopamine
• Histamine
• Serotonin

Question 10

ACh

Answer 10

• Role in wakefulness and REM
• Comes from basal forebrain and the laterodorsal and pendunculopontine nuclei
• LDT and PPT projection to thalamus is most robustly involved in wakefulness
• BF can also lower sleepyness through projection of GABA
• Pushes you into REM sleep

Question 11

Norepinephrine

Answer 11

• Role in wakefulness
• Produced by locus coeruleus
• Optimizes attention and task performance
• Excessive firing can cause insomnia and anxiety at night
• Inhibited by A1 and A2 receptors in a feedback loop (can use BP medications to lessen anxiety and nightmares!)

Question 12

Histamine

Answer 12

• Role in wakefulness
• Produced by tuberomammilary nucleus in posterior hypothalamus
• H1 receptors=wakefulness
• H3 autoreceptors inhibit HA activity so antagonizing H3 receptors promotes wakefulness

Question 13

Serotonin (5HT)

Answer 13

• Generally promotes wakefulness and inhibits REM but there are 15 different receptors that contribute different effects
• Produced in dorsal raphe nucleus
• May push from deep sleep to light sleep

Question 14

Dopamine

Answer 14

• Role in wakefulness
• Produced in substantia nigra (movement), ventral tegmental area (reward)
• Ventral periaqueductal gray in pons fires during wakefulness
• Motivational arousal as opposed to task oriented alertness

Question 15

Orexin/hypocretin

Answer 15

• Not part of RAS
• Excitaroy neuropeptides
• Make in lateral hypothalamus
• Wakefulness regulators
• “back up generator”
• Innervate other wakefulness areas
• Fire only when awake
• Sustain wakefulness

Question 16

Thalamus

Answer 16

• Uses glutamateric neurons to facilitate cortical arousal and GABAergic neurons to dampen ascending arousal pathways when sleep is needed
• Sleep spindles likely to originate here–during REM thalamic neurons are hyperpolarized
• REM and wakefulness–ACh input to those same neurons

Question 17

Suprachiasmatic nucleus

Answer 17

-Governs the 24 hour sleep-wake clock

Question 18

Ventrolateral and median preoptic areas

Answer 18

• Of the lateral hypothalamus
• OFF switch
• Uses GABA and galanin to shut down the wakefulness apparatus
• Fire rigorously during NREM
• MNPO: fires when drifting into sleep
• VLPO: fires while asleep

Question 19

Melanin concentrating hormone

Answer 19

-MCH parallels orexin innervations but dampen other arousal center conversely

Question 20

GABA and Galanin

Answer 20

-Push you into sleep and into deeper sleep

Question 21

What pushes from REM to lighter sleep?

Answer 21

-Norepi, dopa, serotonin

Question 22

Adenosine homeostasis

Answer 22

• Increases while awake during metabolism (ATP breakdown)
• Inhibitory feedback to wakefulness centers and stimulates the VLPO sleep center so sleep occurs
• Caffeine can counter

Question 23

Cytokines interleukin-1B, tumor necrosis factor alpha

Answer 23

• Promote sleep–somnogens
• Increase in the evening
• Derived from brain parenchyma

Question 24

Prostaglandin D2

Answer 24

• Promotes NREM sleep–somnogen

- Synthesized in meninges

Question 25

Homeostatic drive

Answer 25

- Sleep drive increases the longer one stays awake--adenosine builds up - During sleep adenosine converts back to ATP

Question 26

Circadian clock

Answer 26

-Lack of light via optic nerves signals suprachiasmatic nuclei of hypothalamus to allow melatonin release from the pineal gland

Question 27

Melatonin

Answer 27

- May drive 24 hour circadian rhythm - MT1 receptor stimulation dampens ARAS - MT2 receptor stimulation keeps SCN tuned to 24 hr clock

Question 28

Clock genes

Answer 28

- CRY - CLOCK - BMAL1 - PER1 - Fluctuate on a 24 hr basis - Can work in counterphases

Question 29

Zeitgebers

Answer 29

- Gene & environment interactions | - Light, temp, food, exercise, socialization, melatonin, caffeine

Question 30

Brain activity decrease in sleep deprivation

Answer 30

- Anterior cingulate gyrus - Prefrontal cortex - Thalamus

Question 31

Likely cause of narcolepsy

Answer 31

-Bad orexin system

Question 32

Central apnea

Answer 32

- Brain stem forgets to make you breath | - Wear a monitor that wakes you up

Question 33

Obstructive apnea

Answer 33

-Due to weight gain, age, atrophy

Question 34

Leg movements

Answer 34

- Nocturnal myoclonus - Restless legs--creeping sensations, conscious movement - Treat both with D2 receptor agonists

Question 35

Sleep terror disorder

Answer 35

- Unlike nightmares, person has no memory - 1st third of night - NREM (stage 3 or 4)

Question 36

Bruxism

Answer 36

- Teeth grinding | - Stage 2 usually

Question 37

Somniloquy

Answer 37

-Sleeptalking

Question 38

Somnambulism

Answer 38

-Sleep walking

Question 39

REM sleep behavior disorder

Answer 39

- Loss atonia during REM - Act out dreams - D2 agonists treat