Table 1.
Descriptive statistics [mean ± standard deviation (SD)] of sleep electroencephalograph (EEG) variables during morning (MN), afternoon (AN) and evening naps (EN) at ages 2 years (2 Y), 3 years (3 Y) and 5 years (5 Y; no evening nap opportunity provided)
| Morning nap
|
Afternoon nap
|
Evening nap
|
||||||
|---|---|---|---|---|---|---|---|---|
| 2 Y | 3 Y | 2 Y | 3 Y | 5 Y | 2 Y | 3 Y | 5 Y | |
| Children falling asleep (%) | 8/8 (100%) | 8/8 (100%) | 7/8 (88%) | 8/8 (100%) | 5/7 (71%) | 8/8 (100%) | 8/8 (100%) | 5/7 (71%) |
| Time in bed (min) | 116.9 ± 34.2 | 104.3 ± 17.9 | 120.6 ± 30.9 | 90.3 ± 18.4 | 76.0 ± 29.8 | 88.5 ± 21.3 | 75.6 ± 11.0 | 79.2 ± 13.1 |
| Sleep duration (min) | 90.0 ± 37.7 | 68.8 ± 20.0 | 105.2 ± 33.6 | 73.6 ± 21.2 | 63.9 ± 30.9 | 73.9 ± 18.2 | 57.3 ± 8.5 | 64.6 ± 9.6 |
| Sleep latency (min) | 24.3 ± 11.3 | 33.0 ± 14.4 | 13.7 ± 10.2 | 15.1 ± 8.0 | 11.0 ± 4.0 | 13.3 ± 11.5 | 17.0 ± 13.2 | 14.1 ± 8.6 |
| SWS latency (min) | 13.1 ± 3.4 | 14.1 ± 3.7 | 11.6 ± 3.3 | 11.6 ± 5.8 | 13.6 ± 4.1 | 9.2 ± 4.1 | 8.1 ± 2.8 | 7.7 ± 1.4 |
| Stage 2 (min) | 42.7 ± 22.2 | 30.8 ± 16.3 | 40.3 ± 18.8 | 25.9 ± 14.0 | 24.1 ± 9.3 | 24.2 ± 11.7 | 14.0 ± 7.2 | 17.1 ± 9.8 |
| Stage 2 (%) | 45.9 ± 8.9 | 43.4 ± 14.9 | 38.2 ± 12.6 | 34.6 ± 17.8 | 41.8 ± 16.7 | 32.4 ± 13.2 | 25.6 ± 14.9 | 25.4 ± 10.1 |
| SWS (min) | 31.9 ± 9.1 | 25.9 ± 11.6 | 47.1 ± 17.7 | 36.9 ± 14.5 | 25.0 ± 17.3 | 41.5 ± 9.4 | 36.9 ± 11.8 | 42.6 ± 9.5 |
| SWS (%) | 39.7 ± 15.0 | 40.2 ± 21.4 | 47.0 ± 18.0 | 50.0 ± 13.3 | 37.6 ± 19.5 | 57.9 ± 16.4 | 63.6 ± 14.2 | 67.0 ± 17.2 |
SWS: slow wave sleep; percentage values were calculated relative to total sleep time.