Table 2.
Selected EEG Sleep and Cortisol Variables (Mean ± SD) in Controls and Depressed Adolescents (during MDE and Remission)
| Control subjects (n = 16) | Depressed (MDE) (n = 16) | Depressed (remission) (n = 16) | Controls versus MDE | MDE versus remission | |
|---|---|---|---|---|---|
| Sleep architecture | |||||
| Stage 1 sleep (%) | 6.2 ± 1.7 | 6.0 ± 2.1 | 6.2 ± 2.5 | 0.19 | 0.50 |
| Stage 2 sleep (%) | 50.6 ± 6.0 | 50.3 ± 5.2 | 51.2 ± 4.5 | 0.17 | 0.85 |
| Stage 3 sleep (%) | 8.0 ± 2.6 | 8.4 ± 4.0 | 9.0 ± 2.7 | 0.31 | 0.86 |
| Stage 4 sleep (%) | 15.5 ± 3.8 | 14.7 ± 4.0 | 13.5 ± 3.9 | 0.57 | 1.49 |
| REM sleep (%) | 19.6 ± 2.8 | 20.6 ± 2.5 | 20.2 ± 3.5 | 1.03 | 0.42 |
| Sleep continuity | |||||
| Sleep latency (minutes)a | 16.0 ± 7.2 | 25.8 ± 20.5 | 21.5 ± 11.0 | 1.24 | 0.36 |
| Total sleep time (minutes) | 464.1 ± 28.9 | 464.5 ± 28.4 | 469.2 ± 22.4 | 0.04 | 1.40 |
| Sleep efficiency (%) | 93.5 ± 3.2 | 90.9 ± 3.1 | 92.6 ± 2.3 | 2.38* | 2.07 |
| Awake time (minutes) | 9.3 ± 5.5 | 11.3 ± 5.2 | 10.0 ± 5.5 | 1.08 | 0.99 |
| REM measures | |||||
| REM latency (minutes) | 109.1 ± 39.0 | 84.8 ± 26.6 | 88.4 ± 25.3 | 2.06* | 1.76 |
| REM activity (units) | 115.7 ± 30.5 | 148.2 ± 38.5 | 145.8 ± 39.0 | 2.65* | 0.61 |
| REM density (units/minute) | 1.1 ± 0.3 | 1.6 ± 0.4 | 1.7 ± 0.4 | 3.99*** | 1.44 |
| REM duration (minutes) | 90.2 ± 14.8 | 96.2 ± 15.0 | 96.0 ± 17.9 | 1.90 | 0.71 |
| Number of REM episodes | 3.8 ± 0.4 | 4.0 ± 0.5 | 3.8 ± 0.5 | 1.46 | 1.38 |
| Cortisol variables | |||||
| NUFC concentration (ng/mL)a | 14.7 ± 7.7 | 25.7 ± 13.2 | 15.1 ± 6.9 | 2.75** | 5.97*** |
a
Analyses were performed on the logarithm.
*
p < 0.05; **p < 0.01; ***p < 0.0001.
MDE, major depressive episode; REM, rapid eye movement; NUFC, nocturnal urinary free cortisol.