How do you calculate the percentage of time spent in N1 sleep?

How do you calculate the percentage of time spent in N1 sleep?

• A. minutes of N1 / TST × 100
• B. minutes of N1 / TRT × 100
• C. minutes of N1 / TST
• D. minutes of N1 × TST

Answer: (A)

Expressing how much of a night’s sleep is in N1 is about comparing the time spent in N1 to the total time asleep. In sleep scoring, Total Sleep Time (TST) is the sum of all epochs scored as sleep (N1, N2, N3, and REM) and does not include wake periods. To get the percentage, you divide the minutes in N1 by the TST and multiply by 100. This converts the portion into a percent of sleep, not of the entire recording. For example, if N1 lasts 20 minutes and the TST is 180 minutes, the percentage in N1 would be 20/180 × 100 ≈ 11.1%. Using total recording time would skew the value because wake time is included there, and omitting the ×100 would give a proportion rather than a percent, while multiplying minutes by TST would create an unrelated unit.

Expressing how much of a night’s sleep is in N1 is about comparing the time spent in N1 to the total time asleep. In sleep scoring, Total Sleep Time (TST) is the sum of all epochs scored as sleep (N1, N2, N3, and REM) and does not include wake periods. To get the percentage, you divide the minutes in N1 by the TST and multiply by 100. This converts the portion into a percent of sleep, not of the entire recording.

For example, if N1 lasts 20 minutes and the TST is 180 minutes, the percentage in N1 would be 20/180 × 100 ≈ 11.1%.

Using total recording time would skew the value because wake time is included there, and omitting the ×100 would give a proportion rather than a percent, while multiplying minutes by TST would create an unrelated unit.