Table 1.
Characteristics of habitual and non-habitual nappers from screening week
| Habitual nappers | Non-habitual nappers | t/χ2 | p | |||
|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | |||
| n | 48 | – | 43 | – | – | – |
| Age (years) | 16.70 | 1.05 | 16.28 | 0.82 | 2.08 | 0.040 |
| Sex (number of females) | 26 | – | 22 | – | – | |
| Caffeine (drinks per day) | 0.52 | 0.68 | 0.84 | 1.04 | 1.76 | 0.081 |
| Raven’s Progressive Matrices score | 9.58 | 1.80 | 8.49 | 1.82 | 2.89 | 0.005 |
| Epworth Sleepiness Scale score | 8.21 | 3.57 | 7.81 | 3.12 | 0.56 | 0.578 |
| PSQI global score | 4.42 | 1.77 | 4.26 | 1.40 | 0.46 | 0.650 |
| Morningness–Eveningness score | 48.77 | 7.29 | 49.37 | 6.31 | 0.42 | 0.677 |
| Beck Depression Inventory score | 10.50 | 5.85 | 10.47 | 6.05 | 0.03 | 0.978 |
| Beck Anxiety Inventory score | 10.17 | 6.23 | 10.77 | 6.76 | 0.44 | 0.660 |
| Actigraphy measures | ||||||
| Nocturnal TIB on weekdays (h) | 6.70 | 0.73 | 7.34 | 0.73 | 4.18 | <0.001 |
| Nocturnal TIB on weekends (h) | 8.08 | 1.16 | 8.59 | 1.03 | 2.21 | 0.030 |
| Nocturnal TIB on average (h) | 7.09 | 0.61 | 7.69 | 0.62 | 4.63 | <0.001 |
| Nocturnal TST on weekdays (h) | 5.37 | 0.65 | 5.70 | 1.16 | 1.74 | 0.085 |
| Nocturnal TST on weekends (h) | 6.51 | 1.16 | 6.93 | 0.94 | 1.84 | 0.070 |
| Nocturnal TST on average (h) | 5.69 | 0.58 | 6.15 | 0.65 | 3.54 | 0.001 |
| Wake time on weekdays* | 06:53 | 1.38 | 06:59 | 1.20 | 0.40 | 0.689 |
| Wake time on weekends* | 08:40 | 1.71 | 08:42 | 1.26 | 0.14 | 0.887 |
| Wake time on average* | 07:23 | 1.33 | 07:29 | 1.05 | 0.34 | 0.732 |
| Bedtime on weekdays* | 00:13 | 1.51 | 23:39 | 1.00 | 2.06 | 0.042 |
| Bedtime on weekends* | 00:35 | 1.14 | 00:08 | 0.95 | 2.01 | 0.047 |
| Bedtime on average* | 00:19 | 1.31 | 23:47 | 0.88 | 2.23 | 0.028 |
Note. SD, standard deviation; PSQI, the Pittsburgh Sleep Quality Index; TIB, time in bed; TST, total sleep time.
Bold values indicate p values < 0.05.
*Mean = 24 h clock time, SD = h.