Non-Rapid Eye Movement Sleep Arousal Disorders

What Are Non-Rapid Eye Movement Sleep Arousal Disorders?

In sleepwalking, the person gets out of bed and performs behaviours with a blank stare and reduced responsiveness. During a sleep terror, the person may sit up, scream, and show intense fear with rapid heart rate, rapid breathing, and sweating, while remaining difficult to awaken or comfort. Episodes arise from non-rapid eye movement (NREM) sleep rather than rapid eye movement (REM) sleep, when vivid dreaming is more common. Dream imagery is usually minimal or absent, and amnesia for the episode is typical, although fragmentary recall does not by itself exclude the diagnosis.

Key Features and Signs

Episodes range from simple confusion to complex and potentially dangerous behaviours:

• Getting out of bed, walking or performing usual activities with reduced awareness and difficulty waking up.
• Sitting up abruptly, screaming, intense expression of fear, rapid heart rate, sweating, and little response to comforting efforts.
• Blank stare, confusion, and inappropriate responses during or immediately after the episode.
• Little or no memory the next morning, although there may be fragmentary recollection or partial recall.
• Complex behaviours, such as leaving the room, eating, or sexual behaviour in sleep, with varying degrees of awareness.
• Injuries, disturbing the sleep of other household members or a significant safety concern.

How It Is Diagnosed

Diagnosis is based on a detailed history of the episode, often provided by someone who witnessed it. The assessment documents timing, duration, behaviour, responsiveness, recall, injuries, sleep schedule, medications, and possible co-occurring sleep disorders.

• There are repeated episodes of incomplete awakening, usually in the first third of the main sleep period, with sleepwalking or sleep terrors.
• Dream imagery is usually minimal or absent, and amnesia for the episode is typical; these features support the diagnosis but are not stand-alone tests.
• Episodes cause clinically significant distress or impairment in social, occupational, or other important functioning; impairment may also be associated with substantial risk of injury.
• Not explained by a substance or medication, another sleep disorder, neurological or mental condition.

DSM-5-TR criteria include little or no recalled dream imagery and amnesia for the episodes. Recall can vary in clinical assessment; the specialist considers the full history and the diagnostic system being used. No single feature is sufficient for self-diagnosis.

How It Can Affect Daily Life

Sexsomnia requires specialist assessment of safety, consent and the nature of the episodes, without assuming deliberate behaviour.

Factors that trigger or worsen episodes

Non-Rapid Eye Movement Sleep Arousal Disorders have complex biological and familial vulnerability. Episodes may be triggered or worsened by sleep deprivation, irregular schedules, stress, fever, alcohol, certain medications, and conditions that provoke arousals, such as obstructive sleep apnea. Sleep terrors are common in early childhood, but isolated episodes reported in a sample do not equal the prevalence of the clinical disorder. Estimates vary by age, definition, and recording method.

Similar or Co-occurring Conditions

Time, stereotypy of episodes and recall help distinguish:

• Nightmares usually occur in REM sleep, with more complete dream recall and faster full awakening.
• REM sleep behaviour disorder occurs more often later in the night and involves acting out a dream.
• Nocturnal seizures are often brief and highly stereotyped and may require video-electroencephalographic investigation.
• The irregular sleep-wake pattern belongs to circadian rhythm disorders and is not a subtype of NREM parasomnia.
• Rarer dissociative episodes are separate differential diagnosis; sexsomnia (sexual behaviours during sleep) is considered a phenotype of NREM parasomnia.

Treatment and Support

The approach starts with safety and reducing the factors that fragment sleep:

• Make doors and windows safe, remove hazards and obstructions from stairs, and use a low bed if there is a fall risk.
• Maintain a regular schedule and adequate sleep duration, address sleep deprivation, and limit alcohol and other triggers.
• Screening and treating co-occurring disorders, particularly obstructive sleep apnea, restless legs, or other causes of frequent awakenings.
• During the episode, calm guidance away from danger without sudden awakening or physical confrontation, unless required for immediate safety.
• In frequent or dangerous episodes, a sleep specialist may consider scheduled awakenings or, less commonly, drug therapy after a full evaluation.

When to Seek Help

Seek evaluation when episodes are frequent, begin for the first time in adulthood, involve injury, leaving home, sexual or other risky behaviour, occur several times at night, or are accompanied by snoring and pauses in breathing. Safely taken video and sleep diary can help the specialist, without putting anyone in danger for the recording.

Frequently Asked Questions

Should we wake up a sleepwalker?

Priority is to calmly move away from danger. Abrupt awakening may cause confusion or fear, but is not in itself dangerous; if necessary for safety, it is done gently.

If they remember anything, is NREM parasomnia ruled out?

No. There is usually little or no recall, although fragmentary memories may sometimes remain. Diagnosis is based on the overall pattern.

Are sleep terrors the same as nightmares?

No. Sleep terrors usually begin in deep NREM sleep, with reduced responsiveness and little recall. The nightmare usually occurs in REM and the person wakes up more fully and remembers the dream.

Sources

1. American Academy of Sleep Medicine: Practice Guidelines
2. American Academy of Sleep Medicine: Sleep Medicine Toolkit