Sleep disorders

Definition

Sleep disorders involve any difficulties related to sleeping, including difficulty falling or staying asleep, falling asleep at inappropriate times, excessive total sleep time, or abnormal behaviors associated with sleep.

Causes

More than 100 different disorders of sleeping and waking have been identified. They can be grouped in four main categories:

• Problems with falling and staying asleep
• Problems with staying awake
• Problems with adhering to a regular sleep schedule
• Sleep-disruptive behaviors

PROBLEMS WITH FALLING AND STAYING ASLEEP

Insomnia includes any combination of difficulty with falling asleep, staying asleep, intermittent wakefulness and early-morning awakening. Episodes may be transient (come and go), short-term (lasting as long as 2 to 3 weeks), or chronic (long-lasting).

Common factors associated with insomnia include:

• Physical illness
• Depression
• Anxiety or stress
• Poor sleeping environment such as excessive noise or light
• Caffeine
• Alcohol or other drugs
• Use of certain medications
• Heavy smoking
• Physical discomfort
• Daytime napping
• Counterproductive sleep habits:
  • Early bedtimes
  • Excessive time spent awake in bed

Disorders include:

• Psychophysiological insomnia (learned insomnia)
• Delayed sleep phase syndrome -- where a patient's internal clock is constantly out of synch with the "accepted" day / night phases; for example, patients feel best if they can sleep from 4AM to noon
• Hypnotic-dependent sleep disorder -- insomnia resulting from building tolerance to, or stopping, certain types of sleep medications
• Stimulant-dependent sleep disorder -- insomnia resulting depending on, or stopping, certain types of stimulants

PROBLEMS WITH STAYING AWAKE

Disorders of excessive sleepiness are called hypersomnias. These include:

• Sleep apnea
• Narcolepsy
• Restless leg syndrome
• Periodic limb movement disorder
• Obstructive sleep apnea
• Central sleep apnea
• Idiopathic hypersomnia
• Respiratory muscle weakness associated sleep disorder

Sleep apnea more commonly affects obese people, but it may affect anyone with a short neck or a small jaw, regardless of weight. The disorder causes breathing to stop intermittently during sleep, resulting in the person being awakened repeatedly. People with sleep apnea often have difficulty achieving prolonged deep sleep. This results in excessive daytime sleepiness.

Narcolepsy is a condition of daytime sleep attacks as well as other features that may include sleep paralysis and hypnagogic hallucinations (hallucinations that happen at the time between wakefullness and sleep). Sleep attacks occur despite adequate sleep at night. A person with narcolepsy may suddenly fall asleep in any situation, without warning.

Restless leg syndrome is characterized by an uncomfortable sensation, usually in the legs, that occurs primarily at night and when a person is relaxed. The uncomfortable sensation diminishes when the legs are moved. This is commonly associated with periodic limb movement disorder, in which a patient has limb movements during sleep. It usually causes insomnia and may cause daytime sleepiness.

PROBLEMS WITH ADHERING TO A REGULAR SLEEP SCHEDULE

Problems may also occur when maintaining a consistent sleep and wake schedule is disrupted. This occurs when traveling between times zones and with shift workers on rotating schedules, particularly nighttime workers.

Sleep disruption disorders include:

• Sleep state misperception (the person actually sleeps a different amount than they think they do)
• Shift work sleep disorder
• Natural short sleeper (the person sleeps less hours than normal but suffers no ill effects)
• Chronic time-zone-change syndrome
• Irregular sleep-wake syndrome

SLEEP-DISRUPTIVE BEHAVIORS

Abnormal behaviors during sleep are called parasomnias and are fairly common in children. They include:

• Sleep terror disorder
• Sleep walking
• REM sleep behavior disorder (a type of psychosis related to lack of REM sleep and lack of dreaming)

Sleep terror disorder is an abrupt awakening from sleep with fear, sweating, rapid heart rate, and confusion. Sleepwalking is usually not remembered by the person doing it, and usually affects children 2 to 12 years old.

In adults, sleepwalking may also be caused by an organic brain syndrome, reactions to drugs, psychological disorders, and certain medical conditions.