Table 2.
Estimated means (95% CI) and effect sizes of time effects for sleep and psychological measures by group and time (N = 177)
| Variable and group | T1 | T2 | T3 | T4 | T5 |
|---|---|---|---|---|---|
| Insomnia severity (ISI; 0–28; cutoff ≥ 8) | |||||
| StanCBT-I | 15.3 (14.2–16.4) — |
6.0 (4.9–7.2) d = −2.20 |
6.3 (5.1–7.5) d = 0.05 |
6.5 (5.3–7.7) d = 0.06 |
7.1 (5.9–8.3) d = 0.14 |
| StepCBT-I | 15.3 (14.6–16.1) — |
7.2 (6.4–8.0) d = −1.95 |
7.1 (6.3–7.9) d = −0.03 |
6.3 (5.5–7.1) d = −0.18 |
6.9 (6.1–7.8) d = 0.15 |
| Sleep onset latency (min) | |||||
| StanCBT-I | 30.9 (26.4–35.4) — |
15.7 (10.9–20.5) d =−0.87 |
17.3 (12.4–22.1) d = 0.09 |
15.5 (10.6–20.5) d = −0.10 |
16.8 (11.9–21.7) d = 0.07 |
| StepCBT-I | 34.9 (31.8–38.1) — |
17.8 (14.5–21.1) d = −0.98 |
18.9 (15.6–22.2) d = 0.06 |
18.9 (15.5–22.2) d = 0.00 |
20.7 (17.3–24.1) d = 0.10 |
| Wake after sleep onset (min) | |||||
| StanCBT−I | 41.8 (35.3–48.3) — |
20.5 (13.6–27.4) d = −0.84 |
20.2 (13.3–27.2) d = −0.01 |
23.9 (16.9–30.9) d = 0.14 |
20.4 (13.3–27.4) d = −0.14 |
| StepCBT-I | 50.4 (45.8–55.0) — |
29.4 (24.6–34.8) d = −0.83 |
28.7 (23.9–33.5) d = −0.03 |
24.6 (19.8–29.4) d = −0.16 |
28.2 (23.3–33.0) d = 0.14 |
| Total wake time (min) | |||||
| StanCBT-I | 101.0 (90.4–111.6) — |
51.6 (40.3–62.9) d = −1.19 |
54.7 (43.3–66.2) d = 0.08 |
59.0 (47.4–70.6) d = 0.10 |
55.3 (43.7–66.9) d = −0.09 |
| StepCBT-I | 122.8 (115.3–130.3) — |
68.2 (60.4–75.9) d = −1.32 |
67.2 (59.3–75.0) d = −0.02 |
65.2 (57.3–73.1) d = −0.05 |
69.5 (61.5–77.5) d = 0.10 |
| Total sleep time (min) | |||||
| StanCBT-I | 407.4 (391.6–423.2) — |
410.4 (393.8–427.1) d = 0.05 |
417.8 (401.0–434.6) d = 0.12 |
421.3 (404.3–438.3) d = 0.06 |
432.7 (415.7–449.7) d = 0.19 |
| StepCBT-I | 421.3 (410.1–432.5) — |
431.1 (419.7–442.6) d = 0.16 |
438.9 (427.3–450.5) d = 0.13 |
445.4 (433.7–457.0) d = 0.10 |
445.5 (433.7–457.2) d = 0.00 |
| Sleep efficiency (%) | |||||
| StanCBT-I | 80.1 (78.0–82.2) — |
88.6 (86.4–90.8) d = 1.05 |
88.1 (85.9–90.3) d = −0.06 |
87.7 (85.4–90.0) d = −0.05 |
88.4 (86.2–90.7) d = 0.09 |
| StepCBT-I | 77.5 (76.0–78.9) — |
86.3 (84.8–87.8) d = 1.09 |
86.7 (85.2–88.2) d = 0.05 |
87.2 (85.7–88.8) d = 0.07 |
86.4 (84.8–87.9) d = −0.11 |
| Sleep medication (% of users) | |||||
| StanCBT-I | 47.5 (35.1–60.1) |
23.7 (14.6–36.2) |
23.7 (14.6–36.2) |
18.6 (10.6–30.6) |
18.6 (10.6–30.6) |
| StepCBT-I | 46.6 (37.8–55.6) |
27.1 (19.9–35.9) |
27.1 (19.9–35.9) |
23.7 (16.9–32.2) |
24.6 (17.6–33.2) |
| Anxiety symptoms (HADS-A; 0–21; cutoff ≥ 7) | |||||
| StanCBT-I | 7.1 (6.3–8.0) — |
4.4 (3.6–5.3) d = −0.85 |
4.2 (3.3–5.1) d = −0.08 |
4.8 (3.9–5.7) d = 0.19 |
4.8 (3.9–5.7) d = 0.00 |
| StepCBT-I | 6.7 (6.1–7.3) — |
4.9 (4.3–5.5) d = −0.56 |
5.1 (4.5–5.7) d = 0.05 |
4.8 (4.2–5.4) d = −0.07 |
5.0 (4.4–5.6) d = 0.06 |
| Depressive symptoms (HADS-D; 0–21; cutoff ≥ 7) | |||||
| StanCBT-I | 4.5 (3.8–5.3) — |
2.7 (2.0–3.4) d = −0.68 |
2.7 (1.9–3.5) d = 0.00 |
3.0 (2.2–3.7) d = 0.10 |
2.6 (1.8–3.3) d = −0.14 |
| StepCBT-I | 4.5 (4.0–5.0) — |
2.8 (2.3–3.3) d = −0.62 |
3.2 (2.7–3.7) d = 0.14 |
2.9 (2.3–3.4) d = −0.13 |
3.0 (2.4–3.5) d = 0.04 |
| Fatigue (FSI; 0–10; cutoff ≥ 3) | |||||
| StanCBT-I | 4.7 (4.3–5.1) — |
3.4 (2.9–3.8) d = −0.86 |
3.1 (2.6–3.5) d = −0.18 |
3.1 (2.7–3.6) d = 0.05 |
3.3 (2.9–3.8) d = 0.12 |
| StepCBT-I | 5.0 (4.7–5.3) — |
3.9 (3.6–4.2) d = −0.66 |
3.9 (3.6–4.2) d = 0.00 |
3.7 (3.4–4.0) d = −0.13 |
3.8 (3.5–4.1) d = 0.05 |
| Quality of life (QLQ–C33; 0–100) | |||||
| StanCBT-I | 61.5 (56.6–66.4) — |
74.5 (69.3–79.7) d = 0.69 |
75.4 (70.0–80.7) d = 0.05 |
76.1 (70.7–81.6) d = 0.04 |
78.2 (72.7–83.6) d = 0.11 |
| StepCBT-I | 62.3 (58.9–65.7) — |
70.9 (67.3–74.5) d = 0.46 |
71.7 (68.1–75.4) d = 0.04 |
73.1 (69.4–76.8) d = 0.07 |
71.4 (67.7–75.2) d = −0.09 |
For each cell, the first row is the estimated marginal means from the mixed model, the second row (in parenthesis) is the 95% confidence interval around marginal means and the third row is the within-condition effect size (Cohen’s d) between means at this time and previous time (only for continuous variables). ISI, Insomnia Severity Index; HADS-A, anxiety subscale of the Hospital Anxiety and Depression Scale; HADS-D, depression subscale of the Hospital Anxiety and Depression Scale; FSI, Fatigue Symptom Inventory; QLQ, Quality of Life Questionnaire.