Sleep Flashcards
How many stages of slow wave sleep are there?
4
What happens to your muscle tone in REM sleep?
No muscle tone
What are some sleep disorders associated with non REM sleep?
Confusional arousal
Sleep terror
Sleep walking
*Sleep talking occurs in both non REM and REM
What stage of sleep do you enter on falling asleep?
Stage 1 non REM sleep
What is normal sleep architecture?
Cycles of stage 1 through to stage 4 then a period of REM sleep
Cycles typically last 90-120 minutes and a night of sleep is made up of 4 or 5 cycles
What physiological changes occur in REM sleep?
Peaks of parasympathetic and sympathetic activity
Periods of high HR, RR, BP and ventilation
Decreased thermogenesis
Decreased ventilatory response to hypoxia and hypercapnia due to reduced set points during sleep
Vaginal and penile engorgement
What are 3 features of REM sleep?
Inactivity of all voluntary muscles (except extraocular and diaphragm)
Rapid eye movements
Sawtooth waves on EEG
What sleep stage takes up the largest amount of sleep time?
Stage 2 non REM sleep
Changes in sleep on ageing?
Stage 3/4 sleep decreases
Wake time increases
Stage 1 sleep increases
Total sleep time doesnt change
Diagnosis of sleep apnoea?
AHI (apnoea hyponea index) greater then 5 per hour with symptoms
Severe OSA is greater then 30 per hour
What is the most common sleep disorder?
OSA
Risk factors for OSA
Age, male sex Obesity - greatest risk factor Craniofacial abnormalites smoking post menopausal obesity hypoventilation syndrome
What medical conditions can OSA occur in?
pregnancy CHF Hypothyroidism ESRF Chronic lung disease PCOS Acromegaly Stroke/TIA
What are the features of an apnoea in OSA?
episode of reduced airflow lasting for 10seconds at least with associated increase in respiratory effort (as seen by increased activity in EMG over chest and abdomen)
What is the treatment of OSA?
weight loss
CPAP - provides a splint for the upper airway, minimum starting PEEP 4cmH2O
What are some complications of OSA?
Mortality increases by 2-3x
inattention, increased MVA, decreased cognition, depresssion, sexual dysfunction, hypertension, stroke, pul HTN, arrythmias, heart failure, metabolic syndrome, type 2 diabetes
What defines obesity hypoventilation syndrome?
obesity BMI greater than 30 with alveolar hypoventilation (pCO2 greater then 35) during waking hours
Tests in OHS?
High serum bicarbonate
Low oxygen sats during waking hours
Polycythemia
Hypercapnia and hypoxia on ABG during wakefulness
Normal Aa gradient
PSG - large amount of sleep is spent hypoxic, often increased AHI due to co-comitent OSA
What is worse, OHS or OSA?
OSH
- higher mortality
- increased rate of death from PE
- higher rates of CHF and pul HTN
Treatment of OHS?
Immediate start of NIV
if OHS alone - start Bipap
if OHS and OSA - start CPAP but if hypercapnia doesnt improve with resolution of apnoeas change to Bipap
Weight loss, bariatric surgery
Pathology of narcolepsy?
Loss of Orexin (aka hypocretin)
Orexins are usually released in wakefulness to prevent inappropriate transit into REM sleep
Loss of Orexins allows REM sleep phenomenon to intrude into wakefulness
What are the features of narcolepsy?
Excessive daytime sleepiness with sleep attacks
Cataplexy - transient muscle weakness after emotional triggers, consciousness preserved
Hypnagogic hallucinations - vivid frightening hallucinations during falling to sleep
Sleep paralysis
- occurs on awakening unable to move for 1-2 minutes
Diagnosis of narcolepsy?
Multiple sleep latency test
- MSLT less then 8 minutes on two naps
PSG confirms into REM sleep on napping (compared to normal - go into stage 1 sleep)
Low CSF Orexin
Treatment of narcolepsy?
Stimulants for daytime sleepiness
- modafinil, methylpehnidate
Treatment of cataplexy with medications aiming to increase serotonin and NA e.g SSRIs and SNRIs
