Sleep and Sleep Disorders

Sleep and Sleep Disorders
The Science of Sleep
By:Robert Averbuch, MD
Assistant Professor of Psychiatry

Lecture Outline

* Physiology of Normal Sleep
o Non-REM
o REM
o Normal patterns of sleep
* Sleep Disorders
o Dyssomnias
o Parasomnias

Physiology of Normal Sleep

2 Phases: REM and Non-REM Sleep

Non-REM Sleep

* 4 stages of progressively deeper sleep
* Normal muscle tone
* Associated with increased 5HT (serotonin)
* Decreased autonomic activity:
o Lower BP, Pulse, respirations slow

Stage One
* Brief transition between wakefulness and sleep (accounts for only 5% of sleep time)
Stage Two
* Light sleep
* Accounts for 50% of total sleep time
* ElectroEncephaloGram (EEG) shows some characteristic findings…

EEG in Stage 2
Stages 3,4

* Most restful, restorative stages of sleep
* Aka: Delta wave sleep/ slow wave sleep
* Greatest proportion is in the first 1/3 to 1/2 of night

NREM Sleep: Theories of its purpose…

* The decrease in metabolic demand on the brain during NREM allows glycogen stores to replenish
* Allows for consolidation of memories and learning

REM (dreamland)

* 10-20 min. cycles consisting of:
o Rapid Eye Movements
o ElectroEncepahaloGram shows fast activity very similar to wakeful EEG pattern
o Suppression of peripheral muscle tone
o Penile Tumescence
o Often increased autonomic tone- ie, increased blood pressure, resp, heart rate

REM (dreamland)

* Where dreaming occurs
* REM is marked by increased cholinergic activity
o Thus REM-supression seen with anti-cholinergic drugs (ex. some antidepressants)

Normal Sleep Pattern
* Sleep cycles between NREM and REM approx. 4-5 times/night
* Cycles last approx. 90min
* REM duration and frequency increase thru night
* Proportion of slow wave sleep (stages 3,4) decreases thru night

Normal Sleep Parameters
* Sleep Onset Latency- the time it takes one to fall asleep, averages 10-20min
* REM Latency- time between sleep onset and the first REM period, averages 90-120min

Normal Sleep Distribution
* REM sleep accounts for approximately 25% of total sleep time
* Non-REM sleep accounts for 75% of sleep time, with 25% of that spent in Stages 3,4 (most restful portion)

Sleep Onset
* Mediated by increased Serotonergic activity in the Dorsal Raphe Nuclei of the Pons
o Dampens activity in the ascending reticular activating system (RAS), inducing sleep
* Dopamine has opposite effect- promotes wakefulness

Age-Related Changes

* Decreases in dreaming, total sleep time, REM, and slow-wave (deep sleep)
* Increases in early morning awakening, fragmentation, daytime napping, and phase advancement-
o Ie, earlier to bed, and awaken earlier

“Measuring” Sleep
Polysomnography

The Polysomnogram

* EEG, ECG
* EOG (oculogram)
* Chin EMG (myelogram)
* Ant. Tibialis EMG
* Pulse Oxymeter
* Blood Pressure

Sleep Disorders
Sleep Disorders- 2 Divisions

* Dyssomnias- disorders of quality, timing, or amount of sleep (quantity)
* Parasomnias- abnormal behaviors associated with sleep or sleep-wake transition, that often produce arousals

Dyssomnias
* Primary Insomnia
* Narcolepsy
* Sleep Apnea
* Circadian Rhythm Sleep Disorder (jet lag, et al.)
* Restless Legs Syndrome (RLS)
* Medical/Substance related insomnia

Primary Insomnia
* “Primary”, meaning no underlying medical cause
* Onset often with stressor or disruption to sleep schedule or environment
* Results from poor sleep hygiene, along with classical conditioning-
o Faulty learning/association of sleep environment with state of arousal

INSOMNIA- an epidemic?
* Definition: “Subjective” experience of poor sleep quality or quantity that adversely affects daily functioning
* Extremely common complaint in general practice
* 30-40% adults have occasional poor sleep
* 15-20% adults have chronic insomnia

Consequences of Insomnia
* Depression
* Irritability
* Decreased cognitive functioning
* Decreased productivity
* Injuries and accidents

Narcolepsy
* A dyssomnia characterized by poor sleep quality (restless, fragmented) and dysfunction in the transitions between sleep and wakefulness
* Presents with Excessive Daytime Sedation (EDS)

Narcolepsy Tetrad

* Classic tetrad of associated findings:
o 1. Sleep attacks
o 2. Cataplexy
o 3. Sleep paralysis
o 4. Sleep hallucinations

1. Sleep Attacks
* Most common symptom of the tetrad
* Brief (10-20min) “power-naps”- refreshing and restful
* Average 10-20/wk

2. Cataplexy
* Sudden loss of muscle tone (rarely full body paralysis) caused by intrusion of REM activity into daytime wakefulness
* Triggered by heightened emotion
* Average duration: 30 seconds
* No loss of consciousness

3. Sleep Paralysis
* Brief paralysis upon waking
* Remain alert with full eye movements Can occur in the absence of Narcolepsy (ie, normal variant)

4. Sleep Hallucinations
* Hypnogogic hallucinations- occur during transition into sleep
* Hynopompic hallucinations- occur upon awakening from sleep
* Can occur in the absence of Narcolepsy (ie, normal variant)

Narcolepsy: Etiology
* CNS lesions: brain trauma, stroke, tumor, Multiple Sclerosis
* Familial/idiopathic: onset in adolescence or young adulthood

Sleep Apnea
* Dyssomnia characterized by poor sleep quality due to frequent awakenings (apneas)
* Apneas last sec-minutes- produce brief arousal
* Presents with excessive daytime sedation- EDS

Sleep Apnea: Two Types
* Obstructive Sleep Apnea: most common
* Central Sleep Apnea

Obstructive Sleep Apnea
* Classic- obese, middle-aged male with thick neck or enlarged tonsils
* Apneas- brief gasps…silence, followed by loud “resuscitative” snores, and sometimes body movements (restless)
* Usually unaware of snoring, arousals…but sleep partner is aware

Central Sleep Apnea
* Apneas- episodic cessation of central ventilation drive
o Thus snoring is less common
* More in elderly, with underlying CNS lesions- ex. tumor, stroke

Sleep Apnea: Consequences
* Depression
* Anxiety
* Morning headaches
* Cognitive dysfunction
* Hypertension

Restless Legs Syndrome
* Paresthesias and/or dysesthesias in the legs, relieved by movements
* Usually occur in transition from wakefulness to sleep

RLS Causes
* Peripheral neuropathies
* Peripheral vascular disease
* Medication side effects
* Anemia
* Pregnancy
* Renal failure

Circadian Rhythm Disorders
* Delayed Sleep Phase Syndrome
* Jet Lag
* Accelerated Sleep Phase Syndrome
* Shift Work Sleep Disorder

Insomnia from Medical Conditions
* Reflux (GERD)
* Nocturia
* Peripheral neuropathies
* Breathing problems- Asthma, COPD
* Heart Disease/Failure
* Pain conditions

Psychiatric Causes of Insomnia
* Depression
* Anxiety
* Psychosis
* Substance intoxication/withdrawal

Sleep and Sleep Disorders.ppt