Sleep disturbances are common in the general population and among patients with mental disorders. Insomnia is the most prevalent disoreder. Up to 30% of the population suffers from insomnia and seeks help for it. Other conditions include excessive daytime sleepiness, difficulty sleeping during desired sleep time, and unusual nocturnal events, such as nightmares and sleepwalking.

A . Sleep Stages

Sleep is Measured with a polysomnograph, which simultaneously measures brain activity -electroencephalogram (EEG), eay movement -electro-oculogram (EOG), and muscle tone - electromyogram(EMG).Other physiological tests can be applied during sleep and measured along with the adove. EEG findings are used to describe sleep stages.

B. Dyssomnias

1. Primary insomnia:
The trem "primary" indicates that the insomnia occurs independently of any known physical or mental condition. It is characterized by difficulty in falling asleep and repeated awakenings,which continue for at least a month.

2. Primary hypersomnia:
Diagnosed when no other cause for excessive comenolence occuring for at least 1 month can be found. Treatment consistof stimulant drugs (such as amphetamines) given in the morning or evening.

3. Narcolepsy:
a. Characterized by sympton tetrad -- (1) excessive daytime somnolence, (2) cataplex, (3) sleep paralysis, and (4) hypnagogic hallucinnations.

Cataplexy

i . Reported by 70-80% of narcoleptics.
ii . Brief (seconds to minutes) episodes of muscle weekness of paralysis.
iii . No loss of consciousness, if episode is brife.
iv . When attack is over, the patient is completely normal.

Sleep paralysis

a. Reported by 25-50% of general population.
b. Temporary partial or complete paralysis in sleep -wake transitions.
c. Most commonly occurs upon awakening.
d. Conscious but unable to move.
e. Generally lasts less than 1 minute.

Dyssomnianot otherwise specified (NOS)

a. Nocturnal myoclonus
i . Stereotypical leg movement - periodic every 30 seconds.
ii . No seizure activity.
iii . Most prevalent in patients over age 55.
iv . Frequent awakenings.
v . Unrefreshing sleep.
vi . Daytime sleepiness is a major symptom.
vii . Patient is unware of the myoclonus events.
viii. Various drugs have been reported to help. these include clonazepam (Klonopin), opioids,and l-dopa (Larodapa).

b . Restless legs syndrome
i . Uncomfortable sensations in legs at rest.
ii . Not limited to sleep, but can interfere with falling asleep.
iii . Relieved by movement.
iv . Patient may have associated sleep-related myoclonus.
v . Benzodiazepines, e.g.,clonazepam, are the treatment of choice. In severe cases , L-dopa or opioids may be used

c. Menstrual-associated syndrome
Some women experience intermittent marked hypersomnia,altered behaviour patterns and voracious eating at or shortly beforethe onset of menses.

d. Insufficient sleep
Characterized by complaints of daytime sleepiness, irritability, inability to concentrate judgment by a person who persistently fails to sleep enough to support alert wakefulness

C. Parasomnias

1.Nightmare disorder
a. Nightmares almost always occur during REM sleep.
b. Can occur at any time of night.
c. Good recall (quit detailed).
d. Long,frightening dream in which one awakeness frightened.
e. Less anxiety,vocalization, motility ,and autonomic discharge than in sleep terrors.
f. No specific treatment; benzodiazepines may be of help.

2.Sleep terror disorder
a. Especially common in children.
b. Sudden awakening with intense anxiety.
c. Autonomic overstimulation.
d. Movement.
e. Crying out.
f. Patient dose not remember the event.

3.Sleep terror disorder
a. Most common in children; generally disappears spontaneously with age
b. Complex activity - leaving bed and walkeing about with out full consciousness.
c. Amnesia for the event - patient dose not remeber the episode.