Non-REM parasomnias are a group of sleep disorders characterized by undesirable physical or verbal behaviors that occur during non-rapid eye movement (non-REM) sleep stages. These behaviors emerge from an incomplete arousal from deep sleep, where the brain is caught between a sleeping and waking state. Unlike dreams, which typically occur during REM sleep, individuals often have limited or no memory of these episodes. Non-REM parasomnias can range from minor disturbances to more severe, potentially injurious events, impacting both the individual and their bed partners.
Understanding Non-REM Parasomnias
Non-REM parasomnias encompass various specific behaviors, originating from the deeper stages of non-REM sleep. These events involve a partial awakening, where the person exhibits physical actions or vocalizations without full consciousness. Individuals have a blank stare and are unresponsive to attempts to communicate or redirect them during an episode.
Sleepwalking, or somnambulism, is a well-known non-REM parasomnia where individuals get out of bed and move around while still asleep. Activities can range from simply sitting up to performing complex actions like walking, dressing, or even driving, often with eyes open but a distant, “zombie-like” appearance.
Sleep terrors, also known as night terrors, involve sudden awakenings accompanied by intense fear, screaming, and signs of heightened autonomic arousal such as a racing heart rate, rapid breathing, and sweating. The individual is difficult to console and may not recognize familiar people, returning to sleep quickly with no recollection of the episode. These differ from nightmares, which are vivid dreams recalled upon awakening and occur during REM sleep.
Confusional arousals, sometimes called sleep drunkenness, manifest as disorientation and confusion upon waking, often with slow speech and inappropriate responses. The person may seem groggy and struggle to become fully alert.
Sleep-related eating disorder involves involuntary eating during sleep, often of unusual or high-calorie foods, with little to no memory of the consumption. This differs from conscious nocturnal eating syndrome, as individuals are not fully awake during these episodes. Sexsomnia, or sleep sex, describes sexual behaviors performed while asleep.
What Causes Non-REM Parasomnias
Non-REM parasomnias arise from an incomplete dissociation of wakefulness from deep non-REM sleep. Several factors can contribute to or trigger these episodes by disrupting normal sleep architecture or promoting a state of partial arousal. Genetic predisposition plays a role, as these disorders often have a familial link.
Sleep deprivation is a significant trigger, as insufficient sleep can increase the pressure for deep sleep and make complete arousal more difficult. Stress and anxiety also act as common precipitating factors, influencing sleep quality and potentially leading to fragmented sleep. Certain medications, including sedatives, hypnotics, and some antidepressants, can contribute to non-REM parasomnias by altering sleep stages or promoting incomplete arousals.
Underlying sleep disorders, such as obstructive sleep apnea (OSA) or restless legs syndrome, can fragment sleep and increase arousals, exacerbating parasomnia episodes. Fever or illness can also trigger these events as they cause physiological stress. Alcohol consumption before bed can worsen episodes by disrupting sleep continuity and deepening sleep. In children, brain immaturity is a contributing factor, explaining why non-REM parasomnias are more prevalent in childhood and often decrease with age.
Identifying Non-REM Parasomnias
Diagnosing non-REM parasomnias involves a comprehensive assessment by a healthcare professional, relying on a detailed clinical history. The clinician will ask about episode frequency, timing, specific behaviors, and the individual’s level of awareness. Information from family members or bed partners is particularly helpful, as the affected individual often has limited or no recall of the events.
A sleep diary can be a useful tool, where the individual or their caregiver records sleep patterns, episode occurrences, and potential triggers. This diary helps identify patterns and contributing factors. A physical examination also rules out other medical or neurological conditions.
Polysomnography, an overnight sleep study, is not always necessary but may be recommended in specific situations. This test monitors brain waves, muscle activity, heart rate, and breathing during sleep, helping differentiate non-REM parasomnias from other sleep disorders. It is considered for severe cases, injury risk, or unclear diagnoses.
Approaches to Management
Managing non-REM parasomnias involves safety measures, behavioral adjustments, and addressing underlying factors. Prioritizing safety is important for behaviors that could lead to injury. This includes securing windows and doors, and removing hazardous objects from the bedroom.
Optimizing sleep hygiene is a foundational step, as consistent sleep patterns reduce episode likelihood. Establish a regular bedtime and wake-up schedule, create a comfortable and dark sleep environment, and avoid stimulating activities or substances like caffeine and alcohol close to bedtime.
Addressing underlying triggers is also important. This includes managing stress and anxiety. Treating co-existing sleep disorders like sleep apnea is also considered, as they can fragment sleep and contribute to parasomnia. Medications exacerbating the parasomnia should be reviewed and adjusted.
For children with predictable episodes, scheduled awakenings can be an effective technique. This involves waking the child before an anticipated episode, which can interrupt the sleep cycle and prevent the parasomnia. Medication, such as benzodiazepines, may be considered for severe or dangerous cases unresponsive to other interventions. Counseling or therapy can also be helpful. Seek professional help if episodes are frequent, cause injury, significantly disrupt sleep, or lead to distress.