| T&A | Tonsillectomy and adenoidectomy |
| Tachycardia | Rapid heart rate usually defined by a pulse rate of over 100 beats per minute (bpm). |
| TB | Body Temperature |
| TCA | Tricyclic antidepressant |
| Thermal sensors | These sensors are placed near your nose and mouth to detect episodes of apnea by measuring your airflow. They record changes in temperature as you breathe. Air that you exhale is warmer than the air that you inhale. Two types are thermistors and thermocouples. |
| Thermocouples | Small devices placed near the nostrils or mouth to measure air flow by sensing temperature changes; expired air is warmer than inspired air. |
| Thermoregulation | Regulation of body temperature in mammals. |
| Theta waves | EEG activity with a frequency of 4-8 Hz. |
| Thoracic Excursion | 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.. |
| TIB | Time in Bed |
| Tidal Volume | Amount of air that passes in and out of the lungs in an ordinary breath; usually expressed in liters. |
| Titration | Progressive stepwise increase in CPAP pressure applied during a polysomnogram to establish the optimal treatment pressure. |
| Titration | The process of setting the air-pressure level of aPAP device so that it eliminates episodes of apnea and hypopnea. A sleep technologist raises and lowers the air pressure to find the best setting for you. An APAP unit is autotitrating. |
| TLC | Total Lung Capacity |
| TMT | Total Movement Time |
| Tolerance | In pharmacology refers to the reduced responsiveness to a drug's action as the result of previous continued and/or multiple exposure. |
| Tonic (Event/Activity) | Brain muscle or autonomic events which are continuous. Usually refers to continuous activity (e.g. muscle atonia) during REM sleep. |
| Tonsillectomy | Surgical removal of the tonsils. |
| Tonsils | Pair of prominent masses of lymphoid tissue that are located opposite each other in the throat between the anterior and posterior pillars of the fauces (the narrow passage from the mouth to the pharynx situated between the soft palate and the base of the tongue). Composed of lymph follicles grouped around one or more deep crypts. |
| TONSILS | Collection of tissues involved in fighting infection on the side walls of the throat which usually melt away by the age of 8 or so but may persist and partly block the pharynx or throat. |
| Total Recording Time | Duration of time from sleep onset to final awakening. I n addition to total sleep time it is comprised of the time taken up by wake periods and movement time until wake-up. |
| Total recording time | The length of time from “lights out” to “lights on.
total sleep time The total amount of time you spend asleep during the total recording time. |
| Total sleep period | Period of time measured from sleep onset to final awakening. In addition to total sleep time it is comprised of the time taken up by arousals and movement time until wake-up |
| Total sleep time (TST) | Amount of actual sleep time in a sleep period; equal to total sleep period less movement and awake time. Total sleep time is the total of all REMS and NREMS in a sleep period. |
| Tracheostomy | Refers to the opening in the trachea. As a treatment for severe obstructive sleep apnea a tube to assist oxygenation and ventilation and/or to overcome an obstruction in the airway located superiorly. |
| TRACHEOSTOMY (trak-ee-osto-mee) | Creating a hole into the windpipe from outside just below the Adam's apple. Sometimes needed in many different conditions and used to be the main treatment for obstructive sleep apnoea (opened at night closed during the day) to bypass the obstruction in the throat. |
| Tracheotomy | Surgical procedure to create an opening in the trachea (windpipe) so that one can breathe. |
| Transducer | Device designed to convert energy from one form to another. |
| Transient Arousals | Brief awakenings from sleep. |
| Transient Insomnia | Difficulty sleeping for only a few nights. |
| TRD | Tongue retaining device |
| Trec | Rectal temperature |
| TREM | Total REM Time |
| Tricyclic Antidepressants | Medication for depression. Most tricyclic antidepressants also reduce REM sleep; also used to control cataplectic attacks hypnogogic hallucinations and sleep paralysis. |
| TRT | Total recording time |
| TST | Total Sleep Time |
| TSW | Total Slow Wave Sleep (Stage 3 and 4) |
| TT | Total Time |
| Tumescence (penile) | Hardening and expansion of the penis: penile erection. Commonly referred to as nocturnal penile tumescence (NPT) in sleep recordings. |
| 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. |
| Twilight Zone | Slang popular term to describe the waking state of individuals whose MSLT scores are 5 minutes or less. Such individuals are usually sleep deprived or suffer from a sleep disorder. |
| Twitch (Body Twitch) | Very small body movement such as a local foot or finger jerk which is not usually associated with an arousal. |
| TWT | Total Wake Time |
| Tx | Treatment |
| Type 1 sleep study | An overnight sleep study in a laboratory frequently associated with a hospital. This is also called a polysomnogram. |
| Type 2 sleep test | A sleep test that records seven or more channels of information. Recorded signals may include airflow respiratory effort blood oxygen saturation brain activity (EEG) heart activity (EKG) leg movements (EMG) and eye movements (EOG). These are not common. |
| Type 3 sleep test | A home sleep test that records four to seven channels of information. This is the most common type of home sleep test. Recorded signals may include airflow respiratory effort blood oxygen saturation and heart activity (EKG). Many of the home sleep testing protocols including the type used by Sleep Apna H.C. use this type. |
| Type 4 sleep test | A home sleep test that records only one to three channels of information. It may record only blood oxygen saturation using an oximeter. Another recorded measure may be airflow. |
