Table 4.
Animal Fluency Test and Digit Symbol Substitution Test Performance by Sleep Duration (B, 95% CI)
| Linear trend† (≤7 h) | Sleep Duration, Hours per Day | Linear trend† (≥7 h) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| F stat | df | p-value | 2-4 | 5 | 6 | 7 | 8 | 9 | ≥10 | F stat | df | p-value | |
| B (95% CI) | B (95% CI) | B (95% CI) | B (95% CI) | B (95% CI) | B (95% CI) | ||||||||
| Animal Fluency Test | |||||||||||||
| Unadjusted | 3.83 | 1, 15 | 0.0691 | −1.86 (−3.19, −0.52)* | −1.09 (−3.50, 1.32) | −1.39 (−2.47, −0.30)* | Ref. | −0.84 (−2.05, 0.37) | −1.18 (−2.38, 0.02) | −3.78 (−6.16, −1.40)* | 14.38 | 1, 15 | 0.0018 |
| Adjusted‡ | 0.10 | 1, 15 | 0.7613 | −0.22 (−1.61, 1.16) | 0.45 (−1.41, 2.31) | −0.42 (−1.45, 0.60) | Ref. | −0.10 (−1.30, 1.10) | −0.46 (−1.66, 0.74) | −2.90 (−5.68, −0.12)* | 5.54 | 1, 15 | 0.0327 |
| Digit Symbol Substitution Test | |||||||||||||
| Unadjusted | 3.73 | 1, 15 | 0.0726 | −5.58 (−11.67, 0.52) | −5.59 (−10.41, −0.77)* | −3.60 (−7.07, −0.13)* | Ref. | −3.82 (−7.24, −0.39)* | −2.33 (−9.58, 4.93) | −10.05 (−14.54, −5.56)* | 15.47 | 1, 15 | 0.0013 |
| Adjusted‡ | < 0.01 | 1, 15 | 0.9977 | 0.06 (−4.88, 4.99) | −0.10 (−3.90, 3.70) | −0.25 (−3.26, 2.76) | Ref. | −1.17 (−3.87, 1.52) | 1.12 (−4.08, 6.32) | −7.47 (−12.04, −2.91)* | 8.84 | 1, 15 | 0.0095 |
*
P < 0.05
‡
Adjusted for age, sex, race, education, depressive symptoms, and sedative medication use
†
Contrast of marginal linear predictions, df = degrees of freedom, F stat = F statistic, CI = Confidence interval