Sleep and Its Disorders Flashcards
Sleep
The natural periodic suspension of consciousness during which the powers of the body are restored; the intermediate state between wakefulness and death; a reversible behavioral state of perceptual disengagement from unresponsiveness to the environment
Physiologic functions in sleep
The body temperature is at a lower set point, decreased ventilation, and dominance of parasympathetic drive
NREM sleep
Active body, physical restoration, stages N1, N2, and N3
REM sleep
Active brain, atonia, mental restoration
Normal sleep - mammals
All mammals have NREM/REM sleep. All species have REM sleep in early life that tends to decrease with age
What is one of the most important determinants of sleep?
Age
What are the two variables of sleep in human?
The developmental course of Wake/Sleep cycle; the developmental course of the REM/NREM
What is the ratio of REM:NREM sleep for normal sleep in humans?
Infants - 50:50. Adults spend 20-25% in REM and 75-80% in NREM
Slow wave sleep
Largest decline in the second decade of life, stage 2 sleep increases to adult level of 45-55%
Normal sleep in children
Sleep onset REM periods until 3 months old, NREM stages 3-6 months
Normal sleep in adults
Sleep entered through NREM sleep, REM cycles every 90-120 minutes
Normal sleep
NREM sleep predominates in the first half of sleep and is linked to prior level of wakefulness; REM predominates in last half of sleep and is circadian linked
Hypnogram
A graph with the cyclic alteration of wake, REM sleep, and NREM sleep during the sleep period
Homeostatic sleep drive
Sleep responses are proportional to the duration of prior wakefullness - increased sleepiness, increased sleep, increased depth and maintenance of sleep
Circadian rhythms
When isolated from time cues such as sunlight, most creatures show intrinsic rhythms of nearly, but rarely exactly, 24 hours. Generated by the circadian pacemaker located in the syprachiasmatic nuclei (SCN) of the hypothalamus
What do the circadian rhythms include?
Wake/sleep, hormones, temperature, immune function, drug metabolism, renal function, airway function cardiovascular activity, hematoloigcal function, and neoplastic cells
Entrainment
How circadian rhythms are synchronized to the external environment. It is done through presentation of stimuli that signal the time of day called Zeitgebers.
Zeitgebers
Stimuli the signal the time of day; a stimulus capable of shifting the phase of the circadian clock in a systemic manner (photic and non-photic)
Opponent Process Model
The SCN enhances wakefulness and opposes the homeostatic rhythm
Two Process Model of Sleep Regulation (Borbly)
The circadian rhythm, goverened by SCN controls the regulation of awareness/alertness (process C). The sleep-wake homeostasis, or Process S, the accumulation of hypnogenic (sleep-inducing) substances in the brain, generates a homeostatic sleep drive.
Fxn of sleep and sleepiness
Sleep affects all organs of the body, and it remains a biological enigma. Sleep deprivation disrupts biological rhythms.
Determinants of sleepiness
Sleep quantity/sleep quality/circadian factors. The primary determinants of alertness/sleepiness: circadian, homeostatic, age, drugs, sleep disorders. Total sleep requirement and the timing of the wake/sleep cycle are inherent characteristics of an individual
Societal sleep deprivation - chronic and pervasive
As a society, we now get 20% less sleep than our ancestors only 100 years ago. College students oversleep their alarms 50% of the time
Sleep debt
Sleep deprivation is also cumulative. A person does not come to require less sleep or get used to being sleep deprived. Getting less than the necessary amount of sleep starts to create a “sleep debt” which must be paid off. The payback requirement is less than the debt.
Consequences of sleep deprivation
Car accidents, errors in judgement
Safety issues with sleep deprivation.
58% of EM residents reported near crashes driving, 80% of which were post night-shift; increased with the number of night shifts/month. 50% greater risk of blood-borne pathogen exposure incidents (needlestick, laceration, etc) in residents between 10p-6a
Epworth Sleepiness Scale
0 = no chance of dozing; 1 = slight chance of dozing; 2 = moderate chance of dozing; 3 = high chance of dozing. 8 questions about situational chance of dozing and a score of 9 or higher is indicative of sleepiness.
Sleep Testing
Polysomnography; uses EEG, EOG, EMG, leg EMG, airflow, respiratory effort, ECG, and pulse Ox
Visual rules - scoring of sleep stages
Stages of sleep: Stage W (wakefullness); NREM contains: Stage N1 (NREM1), Stage N2 (NREM2), Stage N3 (NREM3). Stage R (REM)
Multiple sleep latency test (MSLT)
Well-validated test of the underlying physiologic tendency to fall asleep during the usual waking hours. It is performed under very controlled conditions. An all night in-lab PSG must precede the MSLT. 5 20min nap opportunities are given at 2hr intervals. Average latency to sleep onset and appearance of REM sleep are measured.
Norms of sleep latency for the MSLT
0-5 minutes indicative of severe hypersomnia; 5-10 minutes is borderline, 10-20 minutes is normal. 2 or more naps with REM periods are abnormal.
Maintenance of Wakefulness Test
Designed to test the patient’s ability to stay awake, The patient is seated upright in bed in a dimly lit room and asked to stay awake for 40 minutes. The test is repeated 4 times throughout the day
Actigraphy
A small recording device worn on the wrist to measure sleep
Sleep disorders
Insomnia, sleep related breathing disorders, hypersomnias of central origin, circadian rhythm sleep disorders, parasomnia
Insomnia
Present for at least a month, evidence of conditioned sleep difficulty or heightened arousal in bed. Treatment includes cognitive behavioral therapies like stimulus control and sleep restriction as well as medications
Obstructive sleep apnea
Symptoms and signs include loud snoring, observed apneas, daytime sleepiness, elevated BMI, crowded oropharynx, hypertension, morning sore throat or headache. Diagnoses is through the polysomnography
Treatment of sleep apnea
Using a positive airway pressure device (CPAP
Restless leg syndrome
Unpleasant limb sensations with the urge to move, symptoms precipitated by rest but get better with movement and get worst in the evening or at night. It causes sleep disturbances and consequences
Hypersomnias of Central Origin: Narcolepsy
Characterized by sleepiness and symptoms due to the abnormal regulation of REM sleep. Symptoms include excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis
Narcolepsy
Prevalence is 0.03-0.05% and the most common age of onset is adolescence. Secondary nacrolepsy can occur in patients with head trauma, stroke, MS, brain tumors, and CNS infections. MSLT found that the mean sleep latency, less than 8 minutes, and 2 or more REM periods in 5 naps is characteristic of narcolepsy
Circadian Rhythm sleep disorders
Delayed sleep phase type, advanced sleep phase type, irregular sleep-wake type, non-entrained type (free running), jet lag type, shift work type, or due to medical condition, substance use, or alcohol
Parasomina
Disorders that intruse into the sleep process and are not primarily disorders of sleep and wake state. Parasomnias are undesirable physical events or experiences that arise from sleep or the sleep-wake transition. It encompasses movements, behaviors, emotions, perceptions, and dreaming
Sleepwalking
Complex automatic motor activity from deep sleep with amnesia of the event, presents with communication difficulty. Major concern for safety/injury because it can encompass a wide range of behaviors, like getting dressed, leaving the house, and driving.
Sleep terrors
Sudden arousals from deep sleep, include screaming, terror, or confusion. Present with extreme autonomic arousal and it is more common in children, as well as males. It can present with variable motor activity (includes extreme agitation)
REM sleep behavior disorder
Dream enactment behavior associated with loss of muscle atonia in REM sleep; includes verbalizations, singing, walking, running, and violent/agitated behaviors (often hitting bed partner)
Sleep related eating disorder
Subcategory of sleepwalking, more common in women than men. It arises from NREM sleep, pt will prepare and eat food, occasionally non-edible objects, but will have total amnesia for the event.
