Table 1.
Participant Characteristics, Sleep Over the Past Week and Sleep Diary Variables for the Insomnia Group and the Normal Sleeper Group
| Insomnia N = 25 | Normal sleeper N = 28 | ||
|---|---|---|---|
| Participant Characteristics | χ2 (1) | ||
| Sex | |||
| Female | 18 | 25 | 2.58 |
| Male | 7 | 3 | |
| t (51) | |||
| Age (in years) | 22.56 (3.14) | 20.82 (1.79) | 2.44 |
| ISI | 16.20 (2.12) | 3.70 (2.14) | 0.00 a ** |
| BDI | 8.74 (5.28) | 4.43 (3.54) | 3.53** |
| STAI-state | 36.28 (10.18) | 32.43 (8.81) | 1.48 |
| STAI-Trait | 45.00 (12.36) | 35.36 (7.91) | 3.42** |
| Duration of Insomnia (months) | 73.35 (78.91) | N/A | N/A |
| Retrospective Estimate of Sleep over the Past Week | t (51) | ||
| SOL | 49.30 (29.84) | 18.57 (9.70) | 86.50 a ** |
| WASO | 34.50 (31.85) | 4.27 (7.36) | 144.00 a ** |
| TST | 6:52 (0:57) | 7:57 (0:50) | −4.39** |
| Sleep satisfaction‡ | 3.66 (1.21) | 7.10 (1.50) | −9.13** |
| Prospective Estimate of Sleep from the Sleep Diary | t (51) | ||
| SOL | 26.48 (18.27) | 17.29 (10.70) | 231.00 a * |
| WASO | 19.31 (12.57) | 8.17 (7.66) | 151.50 a ** |
| TST | 6:55 (0:51) | 7:44 (0:55) | −3.35* |
| Sleep Quality Index Total | 14.20 (2.24) | 16.49 (1.57) | −4.37** |
| Question 1: How well you slept | 3.31 (0.49) | 3.81 (0.51) | −3.61* |
| Question 2: Difficulty falling asleep | 3.61 (0.80) | 4.12 (0.52) | −2.74* |
| Question 3: Restless sleep | 3.57 (0.74) | 4.09 (0.49) | −2.97 |
| Question 4: Early waking and not being able to go back to sleep | 3.71 (0.73) | 4.47 (0.59) | −4.17** |
| Overall sleep quality rating | 5.78 (1.30) | 7.05 (3.07) | 223.00 a * |
Data are presented as mean values with standard deviations in parentheses, except for sex where frequency is reported. ISI = Insomnia Severity Index; BDI = Beck Depression Inventory; STAI = State-Trait Anxiety Inventory; SOL = sleep onset latency; WASO = wake after sleep onset; TST = total sleep time; Overall sleep quality rating: “very bad” to “very good.”
a
Whenever variables were not normally distributed, the Mann Whitney U is reported.
‡
1 = Not at all satisfied, 10 = Very satisfied. *P < 0.01, **P < 0.001.