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Neuro 2 > Sleep > Flashcards

Flashcards in Sleep Deck (41):
1

Sleep

-reversible behavioral state of perceptual disengagement from, and unresponsiveness to the environment
-essential for heath in all mammals (sleep deprivation can be fatal)
-not absence of all brain activity, but series o complex, precisely regulated brain states that are activated & deactivated by multiple sets of diencephalic & brainstem nuclei

2

Sleep Demographics

-normal adults average 7.5 +/- 2 hrs per night
-sleep occupies approximately 1/3 of lifespan
-normal sleep duration dec. with inc. age
-sleep deprivation leads to decreased mental & physical performance & eventually death

3

Biological Clock

-group of cellular/molecular cycles inherent in a variety of body organs that drive a host of circadian rhythms
-contain + & - feedback loops that allow the mechanism to cycle with a regular time constant

4

Suprachiasmatic Nucleus

-anatomical pathway by which ambient light regulates melatonin synthesis and secretion
-rise of melatonin beginning in early evening as daylight wanes & peaking around 2-4 am

5

Polysomnography

-method of measuring sleep

6

Sleep Lab

-sleep room with wall mounts for connecting physiological monitors to the patient
-monitors air flow of nose
-scalp to monitor EEG, face sensors to monitor eyelid movement, monitor respiration, monitor blood ox

7

Sleep frequencies

-5 stages (changes of EEG)
-Beta > 13 Hz
-Alpha 8-13 Hz
-Theta 4-7 Hz (stage I & II)
-Delta <4 Hz (stage III & IV)

-alpha & beta normal awake humans

8

REM stage

-5th
-Rapid Eye Movement
-associated eye movements, physiological changes
-EEG characteristics: fast frequency, low voltage, close to awake state
-theta and beta

9

Sleep Stages (Cycle)

Stage I - IV Non Rapid Eye Movement Sleep or NREM sleep & stage V is rapid eye movement REM
-Frequency (hertz, cps) and voltage
-Stage I sleep is lightest sleep and stage IV is deep sleep
-Stage II is characterized by bursts of activity called sleep spindles and K complexes

10

Stage II Sleep

-unique "spindle" and "K-complex" patterns

11

Sleep Cycle

-starts with Stage I and ends with REM sleep (90 min)
-during duration of stages 3 & 4 sleep lasts longer early in the sleep cycle while REM sleep duration & frequency increase toward the morning or waking hours
-tend to be 5-6 cycles of NREM and REM sleep during a 7-8 hr sleep period

12

Physiologic Changes in Sleep Cycle: NREM sleep

-few eye movements, when they occur they are slow, rolling
-decreased muscle tone but movement still occurs
-decreased HR, BP, RR, temp, metabolic rate
-dreams occur but they are less vivid with low emotional content
-sleep walking and night terrors occur during slow wave sleep
-all changes reach a maximum during stage IV sleep

13

Physiologic Changes in Sleep Cycle: REM sleep

-rapid, ballistic eye movements
-muscle paralysis
-HR, BP, RR, temp., metabolic rate approach awake level
-dreams are vivid with strong emotional content, bizarre
-penile and clitoral erection in REM

14

Neural Sleep Circuits

-awake state: activation of the following nuclei promote wakefulness
Brainstem Nuclei:
-cholinergic neurons in pedunculopontine (PPT) and lateral-dorsal tegmental (LDT) areas
-noradrenergic neurons in the locus ceruleus
-dopaminergic neurons in substantia nigra
-serotonergic neurons in raphe nuclei
Hypothalamic Nuclei:
-histaminergic neurons in tuberomammillary nucleus
-orexin/hypocretin neurons in the lateral hypothalamus

15

Cholinergic Neurons

-from pedunculopontine (PPT) & lateral dorsal tegmental (LDT) areas project to the thalamus and other brainstem areas
-activation signals thalamic-cortical signaling with high frequency, low voltage EEG consistent with arousal and alertness

16

Noradrenergic Circuits

-imput from locus ceruleus to the neocortex is highly activated during wakefulness, less so during NREM sleep, and nearly silent during REM sleep

17

Serotonergic Circuits

-from dorsal and medial raphe nuclei are highly active during wakefulness, less during NREM sleep, and nearly silent during REM sleep
-variety of drugs influence sleep (tricyclic antidepressants & selective serotonin reuptake inhibitors (SSRIs)

18

Histaminergic Circuits

-out put from tuberomammillary nucleus is high during wakefulness, lower during NREM sleep, and still lower during REM sleep
-drugs that block histamine H1 reeceptors, such as diphenhydramine inc. NREM and REM sleep

19

Hypothalamic Nuclei

-suprachiasmatic & paraventricular nuclei involved in the light/dark regulation of pineal gland production of Melatonin

20

Somnogens

-endogenous sleep-promoting chemicals that may accumulate during wakefulness and promote sleep onset
-Adenosine: accumulates in CNS during wakefulness & declines during sleep
-Cytoines: IL-1B and TNF promotes sleep
-Melatonin: Synthesis turned on by dec. light

21

Sleep Symptoms

-Sleepiness
-Insomnia
-Snoring
-Abnormal Behaviors
-Nightmares
-Abnormal Movements

22

Multiple Sleep Latency Test

-EEG defined sleep latency, the time required to fall asleep measured during 4-5 daytime naps

23

Epworth Sleepiness Scale

-self-reported tendency to fall asleep in 8 different situations differing in their soporific nature

24

Obstructive Sleep Apnea (OSA)

-repetitive blockage of the respiratory pathway during sleep causing apneic periods lasting longer than 10 sec and causing oxyhemoglobin desaturations of more than 4%

25

OSA epidemiology

-3-5% of population (4% men, 2% women age 30-60)
-more common in men
-incidence inc. with obesity but occurs also in the non-obese
-strong association b/w OSA, heart disease, HTN

26

OSA Pathogenesis

-complex interaction b/w pharyngeal muscles, tongue, and soft tissues leading to airway obstruction

27

OSA Physical Findings

-Nasal obstruction
-Tonsillar/adenoid hypertrophy
-macroglossia
-reflux laryngitis
-shirt collar size > 17 in
-hypothyroidism with goiter
-truncal obesity
-HTN
-congestive heart failure
-pitting edema of lower extremities
-enlargement of hands & feet (acromegaly)

28

OSA Symptoms

-excessive daytime fatigue
-snoring
-heartburn
-memory loss
-irritability
-depression
-morning headache
-shortness of breath
-nocturia
-impotence

29

Narcolepsy

-excessive daytime sleepiness associated with one or more of the following tetrad
-sleep attacks/intrusions, irresistible, daytime sleep onset
-cataplexy (abrupt loss of muscle tone during waking hours
-sleep paralysis - persistent REM sleep atonia after awakening
-hypnagogic hallucinations - dream persistent after awakening

30

Narcolepsy Epidemiology

-0.05-0.2% (200,000 in US)
-symptom onset 90% develop symptoms by 2nd-3rd decade
-symptoms persist throughout life
-male = female
-familial tendency: 1st deg. relatives have 1-2% inc. risk

31

Secondary Narcolepsy

-associated with multiple sclerosis, pituitary tumors, vascular malformations, stroke

32

Narcolepsy Pathogenesis

-loss of hypocretin/orexin secreting neurons in the posterior lateral hypothalamus related to:
-HLA genes DQ1, DQB1*0602 that may predispose to an autoimmune attack on orexin secreting neurons
-secondary to tumor, stroke, to orexin secreting neurons

33

Naracolepsy Lab

-clinical presentation with components of tetrad
-low CSF hypocretin-1 level (10% normal)
-Polysomnography (mean sleep latency test - MSLT of < 8 min)
-sleep onset REM period >2 episodes of SOREMPs

34

Naracolepsy Treatment

-Daytime sleepiness - methylphenidate, Modafinil, Gama-hydroxybutyrate
-Cataplexy - tricyclic antidepressants, SSRIs

35

Insomnia

-difficulty falling asleep or remaining asleep

36

Epidemiology of Insomnia

-Transient insomnia - days to weeks; affects 50% of adults during lifetime
-Chronic insomnia - >6 weeks, affects 25% of adults
-Female: Male 1.3:1
-Strong association b/w insomnia & depression

37

Insomnia Causes

-delayed sleep onset
-primary: idiopathic, psychophysiologic
-secondary: anxiety, physical activity, jet lag, shift work, sedative withdrawal, stimulant drug use
-Failure to maintain sleep: obstructive sleep apnea, aging, sedative wear-off, depression, REM disorder, medication effects, CNS degenerations

38

REM sleep Behavior Disorder

-loss of atonia/paralysis during REM sleep leading to physical acting out of dream states including verbalization, punching, kicking, jumping from bed; this activity can cause physical injury to the bed partner or patient

39

REM sleep Behavior Disorder: Epidemiology

-RBD present in 0.5% of population
-most common in adult makes over 50

40

REM sleep Behavior Disorder: Pathogenesis

-primary RBD may be idiopathic or associated with alpha-synucleinopathies (parkinsons, multisystems atrophy, lewy body dementia, progressive supranuclear palsy)
-secondary RBD can be caused by EtOH withdrawal, TCA, and SSRI use

41

REM sleep Behavior Disorder: Treatment

-RBD responds well to Clonazepam