Other Sleep Disorders
- Non-Rapid Eye Movement Sleep Arousal Disorders
Non-rapid eye movement (NREM) sleep arousal disorders involve episodes of incomplete awakening from sleep, usually occurring during the first third of a major sleep episode, and are accompanied by either sleepwalking or sleep terrors. The episodes cause significant distress or problems functioning. NREM sleep arousal disorders are most common among children and become less common with increasing age.
Sleepwalking involves repeated episodes of rising from bed and walking around during sleep. While sleepwalking, the individual has a blank, staring face; is relatively unresponsive to others; and is difficult to wake up. Nearly 30% of people have experienced sleepwalking at some time in their lives. Sleepwalking disorder, with repeated episodes and distress or problems functioning, affects an estimated 1% to 5% of people.
Sleep terrors (also called night terrors) are episodes of waking abruptly from sleep, usually beginning with a panicky scream. During each episode, the person experiences intense fear and associated physical signs such as rapid breathing, accelerated heart rate and sweating. The person typically does not remember much of the dream and is unresponsive to efforts of others to comfort them. Sleep terrors are common among very young children—at 18 months of age about 37% of children experience night terrors and at 30 months about 20% experience them. Only about 2% of adults experience night terrors.
Nightmare disorder involves repeated occurrences of lengthy, distressing, and well-remembered dreams that usually involve efforts to avoid threats or danger. They generally occur in the second half of a major sleep episode.
The nightmares are typically lengthy, elaborate, story-like sequences of dream imagery that seem real and cause anxiety, fear or distress. After waking up, people experiencing nightmares are quickly alert and generally remember the dream and can describe it in detail. The nightmares cause significant distress or problems functioning. Nightmares often begin between ages 3 and 6 years but are most prevalent and severe in late adolescence or early adulthood.
- Rapid Eye Movement Sleep Behavior Disorder
Rapid eye movement (REM) sleep behavior disorder involves episodes of arousal during sleep associated with speaking and/or movement. The person’s actions are often responses to events in the dream, such as being attacked or trying to escape a threatening situation. Speech is often loud, emotion-filled, and profane. These behaviors may be a significant problem for the individual and their bed partner and may result in significant injury (such as falling, jumping, or flying out of bed; running, hitting, or kicking). Upon awakening, the person is immediately alert and can often recall the dream.
These behaviors arise during REM sleep and usually occur more than 90 minutes after falling asleep. The behaviors cause significant distress and problems functioning and may include injury to self or the bed partner. Embarrassment about the episodes can cause problems in social relationships and can lead to social isolation or work-related problems.
The prevalence of REM sleep behavior disorder is less than 1% in the general population and it overwhelmingly affects males older than 50.
People with hypersomnolence disorder are excessively sleepy even when getting at least 7 hours sleep. They have at least one of the following symptoms:
- Recurrent periods of sleep or lapses into sleep within the same day (such as unintentional naps while attending a lecture or watching TV)
- Sleeping more than nine hours per day and not feeling rested
- Difficulty being fully awake after abruptly waking up
The extreme sleepiness occurs at least three times per week, for at least three months. Individuals with this disorder may have difficulty waking up in the morning, sometimes appearing groggy, confused or combative (often referred to as sleep inertia). The sleepiness causes significant distress and can lead to problems with functioning, such as issues with concentration and memory.
The condition typically begins in late teens or early twenties but may not diagnosed until many years later. Among individuals who consult in sleep disorders clinics for complaints of daytime sleepiness, approximately 5%–10% are diagnosed with hypersomnolence disorder.
People with narcolepsy experience periods of an irrepressible need to sleep or lapsing into sleep multiple times within the same day.
Sleepiness typically occurs daily but must occur at least three times a week for at least three months for a diagnosis of narcolepsy. People with narcolepsy have episodes of cataplexy, brief sudden loss of muscle tone triggered by laughter or joking. This can result in head bobbing, jaw dropping, or falls. Individuals are awake and aware during cataplexy.
Narcolepsy nearly always results from the loss of hypothalamic hypocretin (orexin)-producing cells. This deficiency in hypocretin can be tested through cerebrospinal fluid via a lumbar puncture (spinal tap). Narcolepsy is rare, affecting and estimated 0.02%–0.04% of the general population. It typically begins in childhood, adolescence or young adulthood.
Restless legs syndrome involves an urge to move one’s legs, usually accompanied by uncomfortable sensations in the legs, typically described as creeping, crawling, tingling, burning, or itching.
The urge to move the legs:
- begins or worsens during periods of rest or inactivity;
- is partially or totally relieved by movement; and
- is worse in the evening or at night than during the day or occurs only in the evening or at night.
The symptoms occur at least three times per week, continue for at least three months, and cause significant distress or problems in daily functioning. The symptoms of restless legs syndrome can cause difficulty getting to sleep and can frequently awaken the individual from sleep, leading, in turn, to daytime sleepiness.
Restless legs syndrome typically begins in a person’s teens or twenties and it affects an estimated 2% to 7.2% of the population.
- Circadian Rhythm Sleep-Wake Disorders
With circadian rhythm sleep-wake disorders, a person’s sleep-wake rhythms (body clock) and the external light-darkness cycle become misaligned. This misalignment causes significant ongoing sleep problems and extreme sleepiness during the day leading to significant distress or problems with functioning.
Circadian rhythm disorders can be caused by internal factors (a person’s body clock is different than the light-dark cycle) or external factors (such as shift work or jet lag).
Prevalence of delayed sleep phase type (staying up late and getting up late) in the general population is approximately 0.17% but estimated to be greater than 7% in adolescents. The estimated prevalence of advanced sleep phase type (going to sleep early and waking early) is approximately 1% in middle-age adults and it is more common in older adults.