Total recording time (TRT) is defined as the interval from lights off to lights on.

Total recording time (TRT) is defined as the interval from lights off to lights on.

• A. 360 minutes
• B. 275 minutes
• C. 300 minutes
• D. 230 minutes

Answer: (A)

Total recording time is the full window the sleep study is recorded, from the moment the lights go off (bedtime) to the moment the lights come on (wake time). This duration includes every minute the patient is in that recording period—whether asleep, awake, or in between. It’s the denominator you use when calculating sleep efficiency, since sleep efficiency = total sleep time divided by total recording time. If the lights are off at one time and the lights come back on six hours later, that TRT is six hours, which is 360 minutes, regardless of how long the patient actually slept. The other numbers would only be correct if the start and end times matched those specific intervals, but by definition TRT is the interval between lights off and lights on.

Total recording time is the full window the sleep study is recorded, from the moment the lights go off (bedtime) to the moment the lights come on (wake time). This duration includes every minute the patient is in that recording period—whether asleep, awake, or in between. It’s the denominator you use when calculating sleep efficiency, since sleep efficiency = total sleep time divided by total recording time. If the lights are off at one time and the lights come back on six hours later, that TRT is six hours, which is 360 minutes, regardless of how long the patient actually slept. The other numbers would only be correct if the start and end times matched those specific intervals, but by definition TRT is the interval between lights off and lights on.