| A | B |
|---|
| Tachycardia | Sinus tachycardia in sleep is defined as a heart rate faster than 90 beats per minute and lasting at least 30 seconds. |
| Thermal sensor | A measure of airflow based on changes in temperature. |
| Theta activity | Activity in the range of 4 to 7 Hz. |
| Tonic | Background or long-lasting activity that provides a contrast to phasic activity. |
| Transcutaneous CO2 | A measure of carbon dioxide in the blood that uses a heated probe to measure the pH of the skin. |
| Transient muscle activity | Brief bursts of EMG activity in the chin or leg EMG lasting less than 0.25 seconds. |
| Vertex sharp waves | Sharp waves lasting less than 0.5 seconds largest in the central channel. |
| Waveform | The shape of a signal. |
| Wide complex | A series of at least 3 heart beats at a frequency of at least 100 beats per minute and with QRS tachycardia duration of 0.12 seconds or longer. |
| Zenith | The highest point or peak of a waveform. |
