Table 3.
Sleep Scoring Parameters (Mean ± Standard Deviation) Derived from Sleep Classification According to R&K and AASM for Young (Y: < 60 Years, n = 25) and Older (O: ≥ 60 Years, n = 31) Healthy Subjects
| Y: Healthy subjects: < 60 years |
O: Healthy subjects: ≥ 60 years |
Y – O |
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|---|---|---|---|---|---|---|---|---|---|---|
| R&K | AASM | Diff. AASM-R&K | P | R&K | AASM | Diff. AASM-R&K | P | Diff. AASM-R&K | P | |
| Lights out clock time (hr:min) | 23:15 ± 0:25 | 23:15 ± 0:25 | - | - | 23:01 ± 0:17 | 23:01 ± 0:17 | - | - | - | - |
| Lights on clock time (hr:min) | 07:16 ± 0:30 | 07:16 ± 0:30 | - | - | 07:04 ± 0:26 | 07:04 ± 0:26 | - | - | - | - |
| Total sleep time (TST; in min) | 422.3 ± 41.6 | 418.0 ± 40.1 | −4.3 | 0.109 | 384.9 ± 56.4 | 382.9 ± 57.0 | −2.0 | 0.241 | −2.3 | 0.921 |
| Total recording time (“lights out” to “lights on” in min) | 478.1 ± 32.9 | 478.1 ± 32.9 | - | - | 481.0 ± 25.4 | 481.0 ± 25.4 | - | - | - | - |
| Sleep latency (SL; in min)* | 16.3 ± 13.7 | 14.2 ± 11.3 | −2.1 | 0.435 | 16.5 ± 14.1 | 16.4 ± 15.0 | −0.0 | 0.914 | −2.1 | 0.493 |
| Sleep REM/R latency (sleep onset to first epoch of Stage R in min) | 82.7 ± 28.1 | 88.4 ± 34.4 | 5.7 | 0.085 | 77.4 ± 35.1 | 44.6 | 6.3 | 0.705 | −0.7 | 0.228 |
| Wake after sleep onset (WASO; Stage W after sleep onset, in min) | 39.8 ± 24.9 | 44.6 ± 28.0 | 4.8 | 0.074 | 74.8 ± 45.9 | 79.9 ± 46.2 | 5.1 | 0.036 | −0.3 | 0.609 |
| Percent sleep efficiency (TST/total recording time)×100 in % | 88.0 ± 6.6 | 87.7 ± 6.5 | −0.3 | 0.590 | 80.6 ± 10.5 | 79.9 ± 10.5 | −0.7 | 0.088 | 0.4 | 0.525 |
| Time in each stage (min) | ||||||||||
| Stage S1/N1 | 42.8 ± 21.4 | 49.5 ± 23.7 | 6.7 | 0.042 | 54.4 ± 24.8 | 66.8 ± 32.0 | 12.4 | 0.001 | −5.6 | 0.245 |
| Stage S2/N2 | 224.1 ± 41.3 | 208.6 ± 43.3 | −15.5 | 0.017 | 214.5 ± 46.8 | 186.3 ± 49.4 | −28.2 | 0.000 | 12.7 | 0.178 |
| Stage S3+S4/N3 | 63.2 ± 31.4 | 72.1 ± 38.2 | 8.9 | 0.091 | 47.0 ± 35.1 | 59.5 ± 44.1 | 12.5 | 0.027 | −3.5 | 0.642 |
| Stage REM/R | 92.2 ± 16.7 | 87.8 ± 19.2 | −4.4 | 0.032 | 69.1 ± 19.3 | 70.4 ± 22.0 | 1.3 | 0.357 | −5.8 | 0.018 |
| Percent of TST in each stage (time in each stage/TST)×100 in % | ||||||||||
| Stage S1/N1 | 10.4 ± 5.5 | 12.1 ± 6.3 | 1.7 | 0.036 | 14.2 ± 6.2 | 17.6 ± 8.2 | 3.4 | 0.001 | −1.7 | 0.187 |
| Stage S2/N2 | 52.8 ± 7.0 | 49.7 ± 8.4 | −3.1 | 0.027 | 55.6 ± 8.2 | 48.4 ± 10.5 | −7.2 | 0.000 | .0 | 0.072 |
| Stage S3+S4/N3 | 14.9 ± 7.2 | 17.2 ± 8.9 | 2.3 | 0.078 | 12.4 ± 9.3 | 15.7 ± 11.7 | 3.3 | 0.026 | −1.0 | 0.594 |
| Stage REM/R | 21.9 ± 3.5 | 21.0 ± 3.9 | −0.9 | 0.061 | 17.8 ± 4.3 | 18.2 ± 5.2 | 0.4 | 0.239 | −1.3 | 0.023 |
The P-values are based on Wilcoxon's matched pairs signed-ranks test (Y, O) or Mann-Whitney U-test (Y – O) for TST, SL, REM/R-latency, WASO and sleep efficiency, for all other variables on paired samples (Y, O) or independent samples (Y – O) t-tests. Numbers in boldface indicate significant results.
*Definition: R&K: lights out to 3 consecutive epochs S1 or the first epoch of any deeper sleep.
AASM: lights out to first epoch of any sleep.