Table 2.
Sleep architecture measures for subjects with (NM) and without (CTL) frequent nightmares
| Night 1 |
Night 2 |
Night 3 |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| General sleep architecture measures | NM (n = 16) Mean (SD) | CTL (n = 11) Mean (SD) | P† | NM (n = 14) Mean (SD) | CTL (n = 11) Mean (SD) | P† | NMs (n = 14) Mean (SD) | CTLs (n = 8) Mean (SD) | P† |
| Total sleep time (min) | 426.4 (56.4) | 410.8 (44.1) | ns | 386.8 (56.6) | 353.1 (57.8) | ns | 398.3 (64.6) | 395.8 (54.8) | ns |
| Sleep efficiency (%) | 95.5 (5.0) | 96.1 (2.1) | ns | 83.1 (8.5) | 81.0 (8.2) | ns | 97.3 (2.8) | 98.7 (1.0) | ns |
| Awakenings (#)a | 14.6 (6.6) | 18.2 (9.9) | nsb | 18.5 (9.5) | 22.8 (13.8) | ns | 12.4 (8.6) | 11.1 (9.5) | ns |
| Wake after sleep onset (min)a | 19.2 (22.8) | 15.9 (8.3) | ns | 76.9 (39.3) | 79.0 (33.4) | ns | 11.0 (12.9) | 5.5 (4.6) | ns |
| Sleep latency (min)a | 11.8 (9.4) | 12.4 (13.5) | ns | 9.4 (7.3) | 10.2 (15.7) | ns | 6.9 (4.4) | 5.8 (3.3) | ns |
| Latency to persistent sleep (min)a | 16.0 (10.9) | 14.0 (14.0) | ns | 10.5 (7.3) | 12.5 (18.3) | ns | 9.6 (7.3) | 6.4 (4.8) | ns |
| Latency to Stage 2 (min)a | 17.1 (11.3) | 14.6 (14.1) | ns | 13.5 (8.6) | 13.7 (18.6) | ns | 10.1 (5.4) | 8.6 (4.8) | ns |
| Latency to Stage 3-4 (min)a | 14.3 (8.9) | 11.5 (6.2) | ns | 13.5 (8.3) | 13.5 (14.0) | ns | 11.6 (7.2) | 9.8 (4.8) | ns |
| Awake (%)a | 4.3 (4.9) | 3.8 (2.1) | ns | 16.0 (8.3) | 18.1 (7.9) | ns | 2.5 (2.8) | 1.3 (1.0) | ns |
| Stage 1 (%)a | 5.6 (3.3) | 4.6 (2.1) | ns | 8.3 (4.5) | 7.3 (4.2) | ns | 5.5 (3.3) | 3.4 (1.4) | ns |
| Stage 2 (%) | 52.9 (8.5) | 49.3 (8.2) | ns | 52.5 (6.5) | 51.0 (8.2) | ns | 46.5 (10.6) | 44.6 (7.7) | ns |
| Stage 3–4 (%) | 21.9 (7.2) | 25.6 (8.5) | ns | 24.2 (7.2) | 27.7 (8.5) | ns | 22.8 (7.5) | 23.5 (6.2) | ns |
| REM sleep measures | |||||||||
| Latency to REM (min) | 115.4 (64.5) | 73.5 (11.1) | 0.021b | 108.2 (66.1) | 83.5 (28.3) | nsb | 66.7 (31.7) | 51.0 (22.8) | ns |
| REM/NREM cycle duration (min) | 112.3 (29.8) | 86.2 (6.9) | 0.004b | 90.7 (28.0) | 78.5 (16.7) | ns | 86.6 (15.0) | 80.5 (6.7) | ns |
| REM periods (#) | 3.8 (0.9) | 4.5 (1.0) | 0.065 | 5.4 (1.7) | 5.5 (1.8) | ns | 4.0 (1.0) | 4.4 (1.1) | ns |
| REM (%) | 19.7 (6.5) | 20.5 (4.8) | ns | 15.0 (5.3) | 14.0 (5.4) | ns | 25.2 (7.6) | 28.5 (3.4) | ns |
| REM efficiency (%) | 85.4 (11.2) | 88.2 (6.0) | ns | 85.1 (12.3) | 83.9 (13.2) | ns | 85.0 (13.1) | 88.7 (5.8) | ns |
| REM fragmentation (#stage shifts within REM period) | 13.9 (7.1) | 14.0 (4.5) | ns | 12.0 (5.3) | 11.7 (4.5) | ns | 15.9 (7.3) | 18.0 (7.2) | ns |
†
2-tailed, independent t-tests, P-values > 0.15 not displayed;
a
Variable log(X+1) transformed for statistical comparisons;
b
Comparison used unequal variance assumption (Levene P < 0.05)