A sleep disorder (somnipathy) is a disorder in the sleep patterns of a person or animal. Some sleep disorders can interfere with mental and emotional function.
The most common sleep disorders include:
Bruxism: The sufferer involuntarily grinds his or her teeth while sleeping
Delayed sleep phase syndrome (DSPS): a sleep disorder of circadian rhythm
Insomnia: Inability to fall asleep and/or remain asleep for a reasonable amount of time.
Jet lag or desynchronosis: Temporary condition resulting in out of sync sleep patterns as a result of rapidly travelling across multiple time zones
Narcolepsy: The condition of falling asleep spontaneously and unwillfully
Night terror or Pavor nocturnus or sleep terror disorder: abrupt awakening from sleep with behavior consistent with terror
Parasomnias: Include a variety of disruptive sleep-related events
Periodic limb movement disorder (PLMD): Involuntary movement of arms and/or legs during sleep. See also Hypnic jerk, which is not a disorder.
Rapid eye movement behavior disorder (RBD): Acting out violent or dramatic dreams while in REM sleep
Restless legs syndrome (RLS): An irresistible urge to move legs while sleeping. Often accompanies PLMD.
Sleep apnea: The obstruction of the airway during sleep
Sleep paralysis: Conscious paralysis upon waking or falling asleep
Sleepwalking or somnambulism: Engaging in activities that are normally associated with wakefulness (such as eating or dressing), which may include walking, without the conscious knowledge of the subject
Snoring: Loud breathing patterns while sleeping, sometimes accompanying sleep apnea
Sleep disorder's treatment from a behavioural standpoint:
First, the underlying cause is identified and eliminated. Behavioural therapy is then the most effective and longest lasting, but also the most time-consuming. Good sleep hygeine includes basically no stimulating substances (caffeine) or activities (exercise) before bed.
Stimulus control therapy involves breaking associations of wakefullness with the sleep environment - otherwise the body will become conditioned to think its "awake time" in the bedroom.
Another behavioural approach involves sleep restriction. A sleep log is kept to determine how much the patient sleeps currently, then they are only allowed to be in bed for that amount of time.
If they don't sleep much during that time, tough luck! they've got to get out of bed. After a couple nights they'll be so sleep deprived that they'll sleep 90% of the allotted time, then you can slowly progress to a more normal sleep interval.