Table 1

Demographic, clinical and polysomnographic information from participants

Group; mean ± SD*Statistical tests†
VariablesControl (n = 27)Insomnia disorder (n = 22)t or χ2dfp value
Age, yr33.4 ± 7.237.5 ± 10.5t = 1.618470.11
Sex, female, no. (%)16 (59.3)12 (54.5)χ2 = 0.11010.74
Duration of insomnia disorder, yr―5.3 ± 5.9
Pittsburgh Sleep Quality Index
 Total score2.4 ± 1.312.3 ± 3.4t = 12.92525.680< 0.001
 Total sleep time, min437.0 ± 44.9254.6 ± 98.0t = −8.07428.131< 0.001
 Sleep efficiency, %95.2 ± 4.562.0 ± 21.2t = −7.22822.517< 0.001
Insomnia Severity Index score1.4 ± 1.818.2 ± 5.4t = 13.99824.996< 0.001
Epworth Sleepiness Scale score3.82 ± 2.96.96 ± 3.8t = −3.265470.002
Dysfunctional Beliefs and Attitutes About Sleep score57.3 ± 20.297.0 ± 22.5t = 6.48947< 0.001
Beck Depression Inventory (non-sleep score)‡2.0 ± 2.18.7 ± 4.4t = −6.48526.534< 0.001
Neuropsychological data of CANTAB
 SOC, mean initial thinking time (5 moves), s5064.48 ± 3448.585632.02 ± 5989.57t = −0.416470.68
 SOC, mean subsequent thinking time (5 moves), s1367.21 ± 2432.042634.85 ± 4485.00t = −1.261470.21
 SOC, problems solved in minimal moves7.7 ± 1.26.6 ± 1.8t = 2.49934.6630.017
Polysomnographic data
 Total sleep time, min390.9 ± 58.9323.8 ± 60.2t = −3.93547< 0.001
 Sleep latency, min5.4 ± 3.816.9 ± 14.1t = 3.75023.4740.001
 Sleep efficiency, %94.5 ± 3.280.3 ± 9.3t = −6.87425.043< 0.001
 Wake after sleep onset, min18.4 ± 14.364.6 ± 43.4t = 4.77924.708< 0.001
 Apnea–Hypopnea Index, n per h2.4 ± 1.62.8 ± 1.7t = 0.872470.39
 Total arousal index, n per h5.3 ± 1.510.0 ± 4.3t = 4.92125.402< 0.001
 Stage N14.4 ± 2.815.5 ± 4.8t = 10.07747< 0.001
 Stage N252.1 ± 9.149.5 ± 7.7t = −1.068470.29
 Stage N318.4 ± 6.612.2 ± 6.6t = −3.260470.002
 Stage R25.1 ± 4.922.9 ± 4.1t = −1.719470.092

  • 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.