Table 1 Comparison of demographic and clinical characteristics among the non-insomnia, insomniac with no hypnotic use, hypnotic user with no insomnia complaints, and hypnotic user with insomnia complaints groups.

From: Difference in spectral power density of sleep electroencephalography between individuals without insomnia and frequent hypnotic users with insomnia complaints

Variables

NI (n = 1386)

INH (n = 401)

HNI (n = 133)

HI (n = 65)

Statistics

Demographics

Age, years

63.5 ± 11.4

64.3 ± 10.9

65.5 ± 11.0

65.6 ± 11.1

F = 2.11, p = 0.097

Sex, female

609 (43.9%)

261 (65.1%)

86 (64.7%)

54 (83.1%)

χ2 = 96.17, p < 0.001

BMI, kg/m2

28.0 ± 5.1

28.1 ± 5.1

28.3 ± 5.6

28.6 ± 5.5

F = 0.37, p = 0.778

Substance or medication

Current smoking

117 (8.4%)

43 (10.7%)

15 (11.3%)

6 (9.2%)

χ2 = 2.76, p = 0.430

Alcohol use per day

2.8 ± 5.4

2.6 ± 5.8

2.2 ± 4.7

1.2 ± 2.7

F = 13.28, p = 0.004

TCA use*

14 (1.0%)

10 (2.5%)

22 (16.5%)

11 (16.9%)

χ2 = 152.55, p < 0.001

Non-TCA use*

30 (2.2%)

20 (5.0%)

38 (28.6%)

5 (7.7%)

χ2 = 191.05, p < 0.001

Benzodiazepine use*

20 (1.4%)

43 (10.7%)

43 (32.3%)

28 (43.1%)

χ2 = 346.59, p < 0.001

Insomnia symptoms§

Sleep initiation difficulty

0 (0%)

179 (44.6%)

0 (0%)

48 (73.8%)

χ2 = 1169.52, p < 0.001

Sleep maintenance difficulty

0 (0%)

226 (56.4%)

0 (0%)

33 (50.8%)

χ2 = 1504.44, p < 0.001

Early morning awakening

0 (0%)

181 (45.1%)

0 (0%)

27 (41.5%)

χ2 = 1229.41, p < 0.001

Taking sleeping pills

0 (0%)

0 (0%)

133 (100%)

65 (100%)

χ2 = 1846.00, p < 0.001

ESS score

7.5 ± 4.5

7.6 ± 4.7

7.2 ± 4.1

6.6 ± 4.8

F = 0.98, p = 0.402

  1. Data are mean ± SD or number (percentage). Statistics were performed using ANOVA, Kruskal–Wallis, or Chi-square tests.
  2. NI, non-insomnia; INH, insomniac with no hypnotic use; HNI, hypnotic user with no insomnia complaints; HI, hypnotic user with insomnia complaints; BMI, body mass index; TCA, tricyclic antidepressant; Non-TCA, non-tricyclic antidepressant; ESS, Epworth Sleepiness Scale.
  3. *TCA, non-TCA, and benzodiazepine use: taking medication within two weeks.
  4. §Presence (or absence) of each insomnia symptom was evaluated by the four questions below and those who reported 1: Never or 2: Rarely (1 × /month or less) were classified as having no insomnia, and those who responded almost always (16–30 × /month) were classified as having insomnia.
  5. Question 1, sleep initiation difficulty: How often do you have trouble falling asleep?.
  6. Question 2, sleep maintenance difficulty: How often do you wake up during the night and have difficulty resuming sleep?.
  7. Question 3, early morning awakening: How often do you wake up too early in the morning and are unable to resume sleep?.
  8. Question 4, taking sleeping pills: How often do you take sleeping pills or other medication to help you sleep?.
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