Sleep Disorders Glossary T

Sleep Disorders Glossary - T


Tachycardia is the rapid heart rate, especially one above 100 beats per minute in an adult .

Teeth Grinding /Bruxism

Teeth grinding is the term that refers to an incessant grinding and clenching of the teeth. Teeth grinding usually occur during sleep. It is also known as Bruxism.

Bruxers (persons with bruxism) are often unaware that they have developed this habit, and often do not know that treatment is available until damage to the mouth and teeth have been done.


Thalamus is the large ovoid mass of gray matter situated in the posterior part of the forebrain that relays sensory impulses to the cerebral cortex.


Thermoregulation is the procedure of regulating body temperature.


Thermoelectric device used to measure temperatures accurately, especially one consisting of two dissimilar metals joined so that a potential difference generated between the points of contact is a measure of the temperature difference between the points.

Theta Activity

Theta Activity is the EEG brain wave activity with a frequency of 4-8 Hz. It is most prominent over the central and temporal cortex.

Thoracic Excursion

Thoracic Excursion is the thoracic (chest) movement, indicating respiratory effort.  Usually measured by the placement of a sensor band, which includes a strain gauge around the chest.  The sensor band records chest wall movement associated with respirations .

Tidal Volume

Tidal Volume is the amount of air that passes in and out of the lungs in an ordinary breath. It is usually expressed in liters.


Titration is the method of determining optimal CPAP treatment parameters for sleep apnea. This involves manual or automatic adjustment of the CPAP device to a level that eradicates airway blockage.


Tolerance in pharmacology refers to the decreased responsiveness to a drug's action as the result of earlier continued use.

Tonic (Event/Activity)

Tonic (Event/Activity) is the brain, muscle, or autonomic events, which are continuous.  Usually refers to continuous activity (e.g. muscle atonia) during REM sleep .


Tonsils are the two masses of tissue on either side of the throat. The tonsils, part of the lymphatic system, help defend the body against harmful microorganisms.


Tonsillectomy is the surgical removal of the tonsils.

Total Sleep Period / Total Recording Time

Total sleep period is the period of time measured from sleep onset to final wakening. In addition to total sleep time, it is comprised of the time taken up by arousals and movement time until wake-up.

It the amount of actual sleep time in a sleep period. It equal to total sleep period less movements and awake time. Total sleep time is the total of all REM and NREM sleep in a sleep period.


Tracheotomy is a surgical procedure that opens up the windpipe (trachea). It is performed in emergency situations, in the operating room, or at bedside of critically ill patients.

The term tracheostomy is sometimes used interchangeably with tracheotomy. Strictly speaking, however, tracheostomy usually refers to the opening itself while a tracheotomy is the actual operation.


Transducer is a device, such as a piezoelectric crystal, microphone, or photoelectric cell, which converts input energy of one form into output energy of another .

Transient Arousals

Transient Arousals is brief awakenings from sleep.

Transient Insomnia

Transient Insomnia is difficulty sleeping for only a few nights. It is sometimes called adjustment sleep disorder or situational insomnia, it is sleeplessness that lasts a few consecutive nights and is often triggered by stress or excitement.

Tricyclic Antidepressants (Antidepressants)

Tricyclic Antidepressants (Antidepressants) is any of a group of antidepressant drugs, such as amitryptyline, that contain three fused benzene rings and that block the reuptake of the neurotransmitters norepinephrine and serotonin in the central nervous system.


Turbinate - Small, shelf-like, cartilaginous structures covered by mucous membranes, which protrude into the nasal airway to help warm, humidify, and cleanse inhaled air on its way to the lungs. It is also called the nasal concha.

Turbinate Reduction

Turbinate Reduction is a surgical treatment used to reduce the size of an enlarged turbinate, which can improve the size of the nasal airway, thereby treating obstructive sleep apnea.

Twilight Zone

Twilight Zone is a slang term that explains the waking state of individuals whose MSLT scores are 5 minutes or less. These kind of individuals are usually sleep deprived or suffer from a sleep disorder.

Twitch (Body Twitch)

Twitch (Body Twitch) is to draw, pull, or move suddenly and sharply or jerk that is not usually associated with an arousal.


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