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Sleep Disorders


Physiology Of Sleep
Sleep pattern are clinically described by sleep architecture ,which is recorded by polysomnography. EEG, Electro-oculograme (EEG), and surface electromyogram are monitored here. Polysomnography pattern divides two types of sleep- REM and NREM.

Stages of sleep
(Stage 0) Wakefulness EEG shows low voltage fast waves, with mix of alpha and beta waves.
Eyes closed – alpha waves-
NREM (non rapid eye movement sleep ) – S sleep (synchronized sleep)

Stage 1 : Absence of a waves theta waves appear (transition between wakefulness & sleep)
Stage 2 : Sleep spindles – 13-15/sec (With background of theta-wave) K Complexes
Stage 3 : Delta waves < 50%
Stage 4 : Delta waves >50%

Normally after 90 min. follows REM sleep
REM- D or desynchronized sleep or paradoxical sleep (This is the stage wherein dreaming occurs) EEG show saw tooth  wave pattern EMG activity is absent reflecting the complete brainstem mediated muscle atonia that is characteristic of that stage.

is characterized by
  1. Generalized muscular atony
  2. Penile and clitoral enlargement
  3. Autonomic activity increases (Fluctuation, respiration heart rate gastric secretion).
  4. 4-5 REM / night

Latency (time between failing asleep and REM) decreased in Narcolepsy . Sleep Deprivation
Long sleepers > 9 hours Short < 6 hours
Sleep Deprivation for > 100 hrs – Psychiatric symptoms specially psychosis.

Sleep cycle vanes with age.

Infancy – Newborns spend around 20 hours in sleep per day. NREM & sleep are not fully differentiated upto 3 to 6 months of age. Circadian rhythm develops over 3 year of life.

Adulthood – decrease in slow wave sleep.

Senescence – Decreased stage 3 and 4 of NREM and REM sleep. Increased stage of 1 and 2 NREM.
Thus loss of diurnal sleep- wake pattern.

Sleep investigation: Polysomnography that studies EEG, ECG, EMG, penile tumescence

Disorders of sleep and wakefulness

  1. Dyssomnias      
  2. Parasomnias
  3. Sleep disorders associated with medical or psychiatric disorders.
  1. Dyssomnias
    1. Insomnia – Complaint of inadequate sleep is prominent can be initial insomnia (difficult in initiating sleep) middle insomnia (difficulty in maintaining sleep), late insomnia or early morning insomnia seen in endogenous depression). Decrease in REM latency occurs in depression. REM latency is used experimentally as a marker to predict treatment response to antidepressants.
      Dyssomnia associated with limb movements:
      Periodic movements is sleep Nocturnal myoclonus – Drug of choice is Benzodiazepines Restless leg syndrome – Ekbom syndrome, during waking – discomfort in leg muscles Drug of choice – Pramipexole, Ropinirole, (Dopamine agonist)
    2. Hypersomnia – 
      1. Narcolepsy:
        Hallmark – Decreased REM latency (time between falling asleep and first REM, normal is 90 minutes)
Tetrad of Narcolepsy
  1. Sleep attack (M/C)
  2. Cataplexy – loss of muscle tone – Precipitated by emotion
  3. Hypnogogic & Hypnopompic hallucinations
  4. Sleep paralysis
  5. Abnormal REM Intrusion is EEG
Drug of choice - Modafinil
- Amphetamine - Methylphenidate
- Imipramine is drug of choice when cataplexy is a prominent symptom.
  1. Sleep apnea
    Cessation of Airflow = 10 second; more than or equal to 30 episodes per night. Seen in
  • Pickwickian syndrome, Obese
  1. Kleine Levin Syndrome :  
    More common in males, in second decade
    Hypersomnia, hyperphagia, hypersexuality
  1. Disorder of Sleep - wake Schedule - These are charcterised by a disturbance of timing of sleep, the various causes are
    1. Jet lag or rapid change of time zone.
    2. Work-shift from day to night or vice-versa.
    3. Unusual sleep phases.
  1. Parasomnias
    The term parasomnia refers to behavior disorder during sleep that are associated with brief or parital arousal but not with marked sleep disruption or impaired daytime alertness. The usual complaint is related to the behavior problem.
Stage IV disorders:
  1. Sleepwalking (Somnambulism)
    Automatic motor activities in unconscious state in state 3 and 4 NREM
  2. Sleep Terror or night terror or pavor nocturnus
    Usually in children, disturbance is in arousal as in sleepwalking. Occurs in NREM phase of sleep cycle.
  3. Sleep Bruxism
    Involuntary forceful grinding of teeth during sleep that affects 10-20% of the population. Typically starts at the age of 17-20 years. Treatment is for the risk of dental injury with rubber tooth guard or relaxation for stress management.
  4. Sleep Enuresis
    Also called bedwetting. Considered normal before the age of 5 years. In older patients enuresis can be primary.
Secondary – bedwetting in those individuals who had been fully continent for 6 to 12 months. The important causes are:
  1. Emotional disturbances.          
  2. Urinary tract infection
  3. Cauda equina lesions                
  4. Epilepsy
  5. Sleep apnea.                                              
  6. Urinary tract malformations               
Pharmacotherapy includes imipramine (DOC) oxybutynin chloride and intranasal desmopressin in some cases.
  1. Sleep-talking (somniloquy):the person talks during stage4(and 3)of NREM sleep but does not remember anything about it on awakening.
    These disorder are often co-existent arousal is difficult and on waking up there is complete amnesia for the events.
Benzodiazepines suppress stage4 of NREM sleep, it provides relief in parasomnias.
Other Sleep Disorder
Nightmares occur during the REM-sleep. They are characterized by fearful dreams occurring most commonly in the last one-third of night sleep. The person wakes up very frightened and remembers the dream vividly.

Classification of Hypno-sedative drugs
  1. Barbiturates
    Long acting                            Short acting                       Ultra-short acting
    Phenobarbitone                   Butobarbitone                      Thiopentone
    Pentobarbitone                    Methohexitone
  2. Benzodiazepines
    Hypnotic               Antianxiety                       Anticonvulsant    
    Diazepam             Diazepam                         Diazepam
    Flurazepam           Chlordiazepoxide               Lorazepam
    Nitrazepam           Oxazepam                         Clonazepam
    Alprazolam            Lorazepam                        Clobazam
    Temazepam           Alprazolam                        Triazolam
  3. Newer non benzodiazepine hypnotics
    Zopiclone              Zolpidem                               Zaleplon
Some pharmacokinetic and clinical features of benzodiazepines used as hypnotics

Drug       t 1/2 (hr. )                           
  1. Long Acting                                          
    Flurazepam           50-100   Diazepam 30-60   Nitrazepam 30
  2. Short Acting                                         
    Alprazolam            12           Temazepam 8-12 Triazolam 2-3

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