Table 5.
Cognitive function at Phase 7 by change in number of hours sleep between Phase 5 and Phase 7 in women and men combined
| Cognitive Function Test# | Change in hours of sleep between Phase 5 and Phase 7 |
||||
|---|---|---|---|---|---|
| Increase from 5 or 6 ha | Participants with no change in sleep duration | Decrease from 6, 7, or 8 hb | Increase from 7 or 8 hc | ||
| Number | 823 | 3047 | 1096 | 451 | |
| A Adjusted for age, sex and education | |||||
| Memory | 0.30 (−0.54, 1.14) | Ref | −0.27 (−0.96, 0.42) | −1.09 (−2.07, −0.10) | |
| AH4-I (reasoning) | 0.06 (−0.73, 0.86) | Ref | −1.44*** (−2.09, −0.79) | −1.36* (−2.29, −0.43) | |
| Mill Hill (vocabulary) | 0.26 (−0.55, 1.06) | Ref | −1.05** (−1.71,−0.39) | −1.62** (−2.56, −0.68) | |
| Phonemic fluency | −0.21 (−1.05,0.62) | Ref | −0.59 (−1.27, 0.09) | −1.35* (−2.33, −0.38) | |
| Semantic fluency | 0.11 (−0.71, 0.93) | Ref | −0.90* (−1.57, −0.23) | −1.66** (−2.62, −0.70) | |
| MMSE | −0.19 (−1.06, 0.68) | Ref | −1.34** (−2.05, −0.63) | −1.85* (−2.87, −0.83) | |
| B Adjusted for age, sex, education and occupational position at Phase 7 | |||||
| Memory | 0.23 (−0.61, 1.06) | Ref | −0.12 (−0.80, 0.57) | −0.98 (−1.96, −0.01) | |
| AH4-I (reasoning) | −0.13 (−0.87, 0.61) | Ref | −1.08** (−1.69, −0.47) | −1.11* (−1.98, −0.25) | |
| Mill Hill (vocabulary) | 0.09 (−0.67, 0.85) | Ref | −0.72* (−1.34, −0.10) | −1.39** (−2.28, −0.50) | |
| Phonemic fluency | −0.34 (−1.15, 0.47) | Ref | −0.33 (−0.99, 0.33) | −1.19* (−2.14, −0.25) | |
| Semantic fluency | −0.04 (−0.82, 0.75) | Ref | −0.62 (−1.27, 0.02) | −1.47** (−2.39, −0.55) | |
| MMSE | −0.26 (−1.12, 0.60) | Ref | −1.19* (−1.90, −0.49) | −1.73** (−2.74, −0.72) | |
Mean difference in score (95% confidence interval)
≤ 5 or 6 h sleep at Phase 5 – more than 5 or 6 hours respectively at Phase 7, reference group is either ≤ 5 or 6 h at both phases (n = 1183 [68+243+120+752 - see Table 4])
6, 7 or 8 h sleep at Phase 5 and < 6, 7, or 8 h, respectively, at Phase 7, reference group is either 6, 7, or 8 h at both phases (n = 2798 [243+284+118+752+1103+298 - see Table 4])
7 or 8 h sleep at Phase 5 and > 7 or 8 h respectively at Phase 7, reference group is either 7 or 8 h at both phases (n = 1803 [284+118+1103+298 - see Table 4])
P < 0.05,
P < 0.01, and
P < 0.001 for difference from no change group
The critical values determining the significance of each test have been adjusted to allow for the multiple comparisons in this table (see methods section).