Sleep Disorders Glossary N

Sleep Disorders Glossary - N


Nap is to sleep for a brief period, often during the day .


Narcolepsy is a chronic (long lasting) disease of the brain (central nervous system). Excessive daytime sleepiness (EDS) is the main symptom and is present in 100% of patients with narcolepsy.

Narcolepsy is a sleep disorder that causes overwhelming and severe daytime sleepiness that often occurs at inappropriate times and places, even after adequate nighttime sleep.

Nasal Airflow/Nasal Ventilation

Nasal Airflow/Nasal Ventilation is a recording of the respiratory cycle by measuring inspiratory and expiratory airflow. It is measured through heat or pressure changes at the nares.

This value is usually recorded in both diagnostic sleep studies and CPAP titration sleep studies. In diagnostic sleep studies it is referred to as nasal ventilation or respiratory airflow.

National Commission on Sleep Disorders Research

The U.S. Congress created national Commission on Sleep Disorders Research in 1990. The commission conducted a comprehensive study of the social and economic impact of sleep disorders in America, and made recommendations based on its findings to Congress in January of 1993.

Natural short sleeper

A natural short sleeper is someone who habitually and spontaneously sleeps substantially less in a 24-hour period than is expected for a person in his or her age group, and does not have excessive sleepiness.

Negative sleep conditioning

Negative sleep conditioning is a psychological state caused by self-induced stress and anxiety of needing to achieve sleep; particularly, it refers to an incapability to sleep at night in one's own bed.


Neurology is the branch of medical science that deals with the nervous system and disorders affecting it .


Neuron is a cell specialized to conduct and generate electrical impulses and to carry information from one part of the brain to another.


Neurotransmitter is a chemical produced by neurons that carries messages to other neurons. Neurotransmitters are chemicals that allow the movement of information from one neuron across the gap between it and the adjacent neuron.

The release of neurotransmitters from one area of a neuron and the recognition of the chemicals by a receptor site on the adjacent neuron causes an electrical reaction that facilitates the release of the neurotransmitter and its movement across the gap.


Nightmares are scary dreams. Nightmares awake the children and make them afraid to go back to sleep. One out of every 4 children has nightmares more than once a week.

Nightmares may happen for no known reason, but sometimes occur when your child has seen or heard things that upset him/her. Most nightmares happen very late in the sleep period (usually between 4 a.m. and 6 a.m.).

Night Owl/ Night Person/Evening Person

Night owl is a person who habitually stays up and is active late into the night. Night owl is also known as night person or evening person

Night Terrors

Night terrors, also known as sleep terror or pavor nocturnus, is a parasomnia sleep disorder characterized by extreme terror and a temporary inability to regain full consciousness. Night terrors happen during deep sleep.


Nocturia is excessive urination at night. It is common in older men. It is also called as nycturia.


Nocturnal is relating to, or occurring in the night. It pertains to events that happen during sleep or the hours of darkness.

Nocturnal Confusion

Nocturnal Confusion is the episodes of delirium and/or disorientation close to or during nighttime sleep. It is mostly seen in the victims of Alzheimer's disease and more common in the elderly.

Nocturnal Enuresis

Nocturnal Enuresis refers to the passage of urine during sleep, whether in the clothing during the day or in bed at night. It is the medical term for Bedwetting.

Non 24-hour sleep wake disorder

Non 24-hour sleep wake disorder also termed non-24-hour circadian rhythm disorder or hypernychthemeral syndrome, is a sleep disorder in which a person's internal clock runs longer than 24 hours.

The person's body essentially insists that the day is longer than 24 hours, which may not allow socially accepted sleeping patterns and make it difficult for the sufferer to sleep at "normal times.".

Nocturnal Myoclonus

Nocturnal myoclonus is a condition in which a person's legs or arms twitch or move involuntarily and periodically during sleep. Nocturnal myoclonus is the medical term for name of Periodic Limb Movement Disorder.

Nocturnal sleep-related eating disorder (NS-RED)

Nocturnal sleep-related eating disorder (NS-RED) is characterized by abnormal eating patterns during the night. Sleep eating is a sleep disorder that causes furious, uncontrolled nighttime eating urges.


Non-Invasive is a medical procedure which does not penetrate or break the skin or a body cavity, i.e., it doesn't require an (invasive) incision into the body or the removal of biological tissue .

Non-REM sleep

Non-REM sleep - a state of sleep divided into 4 stages. These stages progress in a cycle from stage 1 to Rapid eye movement sleep, then the cycle starts over again with stage 1. Each stage represents a different physical and mental state of the body during sleep.

Normal hypersomnia

Normal hypersomnia is a sleep disorder in which a person sleeps requires more sleep than normal, i.e. more than 10 hours of sleep per day, and which may be the result of a genetic predisposition. Normal hypersomniacs are also called "naturally long sleepers."

NREM-REM Sleep Cycle / Sleep Cycle

NREM-REM Sleep Cycle is a period during sleep composed of a NREM sleep episode followed by a REM sleep episode. Each sleep cycle is equal to each NREM-REM sleep couplet with the average duration in adults being 90 minutes. An adult sleep period of 6.5-8.5 hours generally consists of four to six cycles.

NREM Sleep Intrusion

NREM Sleep Intrusion is brief periods of NREM sleep patterns appearing in REM sleep, outside of its usual sleep cycle position.

NREM Sleep Period

NREM Sleep Period is the NREM sleep portion of NREM-REM sleep cycle.


Nyctophobia is the abnormal fear of the night or darkness. It is also called scotophobia .


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