Table 1.
Demographic, clinical and polysomnographic information from participants
| Group; mean ± SD* | Statistical tests† | ||||
|---|---|---|---|---|---|
|
|
|
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| Variables | Control (n = 27) | Insomnia disorder (n = 22) | t or χ2 | df | p value |
| Age, yr | 33.4 ± 7.2 | 37.5 ± 10.5 | t = 1.618 | 47 | 0.11 |
| Sex, female, no. (%) | 16 (59.3) | 12 (54.5) | χ2 = 0.110 | 1 | 0.74 |
| Duration of insomnia disorder, yr | ― | 5.3 ± 5.9 | |||
| Pittsburgh Sleep Quality Index | |||||
| Total score | 2.4 ± 1.3 | 12.3 ± 3.4 | t = 12.925 | 25.680 | < 0.001 |
| Total sleep time, min | 437.0 ± 44.9 | 254.6 ± 98.0 | t = −8.074 | 28.131 | < 0.001 |
| Sleep efficiency, % | 95.2 ± 4.5 | 62.0 ± 21.2 | t = −7.228 | 22.517 | < 0.001 |
| Insomnia Severity Index score | 1.4 ± 1.8 | 18.2 ± 5.4 | t = 13.998 | 24.996 | < 0.001 |
| Epworth Sleepiness Scale score | 3.82 ± 2.9 | 6.96 ± 3.8 | t = −3.265 | 47 | 0.002 |
| Dysfunctional Beliefs and Attitutes About Sleep score | 57.3 ± 20.2 | 97.0 ± 22.5 | t = 6.489 | 47 | < 0.001 |
| Beck Depression Inventory (non-sleep score)‡ | 2.0 ± 2.1 | 8.7 ± 4.4 | t = −6.485 | 26.534 | < 0.001 |
| Neuropsychological data of CANTAB | |||||
| SOC, mean initial thinking time (5 moves), s | 5064.48 ± 3448.58 | 5632.02 ± 5989.57 | t = −0.416 | 47 | 0.68 |
| SOC, mean subsequent thinking time (5 moves), s | 1367.21 ± 2432.04 | 2634.85 ± 4485.00 | t = −1.261 | 47 | 0.21 |
| SOC, problems solved in minimal moves | 7.7 ± 1.2 | 6.6 ± 1.8 | t = 2.499 | 34.663 | 0.017 |
| Polysomnographic data | |||||
| Total sleep time, min | 390.9 ± 58.9 | 323.8 ± 60.2 | t = −3.935 | 47 | < 0.001 |
| Sleep latency, min | 5.4 ± 3.8 | 16.9 ± 14.1 | t = 3.750 | 23.474 | 0.001 |
| Sleep efficiency, % | 94.5 ± 3.2 | 80.3 ± 9.3 | t = −6.874 | 25.043 | < 0.001 |
| Wake after sleep onset, min | 18.4 ± 14.3 | 64.6 ± 43.4 | t = 4.779 | 24.708 | < 0.001 |
| Apnea–Hypopnea Index, n per h | 2.4 ± 1.6 | 2.8 ± 1.7 | t = 0.872 | 47 | 0.39 |
| Total arousal index, n per h | 5.3 ± 1.5 | 10.0 ± 4.3 | t = 4.921 | 25.402 | < 0.001 |
| Stage N1 | 4.4 ± 2.8 | 15.5 ± 4.8 | t = 10.077 | 47 | < 0.001 |
| Stage N2 | 52.1 ± 9.1 | 49.5 ± 7.7 | t = −1.068 | 47 | 0.29 |
| Stage N3 | 18.4 ± 6.6 | 12.2 ± 6.6 | t = −3.260 | 47 | 0.002 |
| Stage R | 25.1 ± 4.9 | 22.9 ± 4.1 | t = −1.719 | 47 | 0.092 |
CANTAB = Cambridge Neuropsychological Test Automated Battery; SD = standard deviation; SOC = Stockings of Cambridge from the Cambridge Neuropsychological Test Automated Battery.
*
Unless otherwise specified.
†
Statistical tests were performed using the Student t test (for equal variance) or Welch t test (for unequal variance).
‡
Beck Depression Inventory (non-sleep score): excluding the sleep item (16) from the total Beck Depression Inventory 21-item score.