Table 1.
Participant Characteristics
| Early sleep timing | Late sleep timing | P-value | |
|---|---|---|---|
| Midpoint of sleep before 03:04 am (n = 122) |
Midpoint of sleep after 03:04 am (n = 121) |
||
| Age at sleep study, years, mean (SD) | 73.785 (4.996) | 73.589 (5.536) | .7717 |
| Sex, number of females (%) | 59 (48.361%) | 68 (56.198%) | .2213 |
| Race, number of African Americans, n (%) | 7 (5.738%) | 17 (14.05%) | .0299 |
| Clinical Dementia Rating, n CDR + (% = 0.5) | 25 (20.492%) | 22 (18.182%) | .6485 |
| APOE ε4 status: n APOE ε4 + (%) | 45 (36.885%) | 42 (34.711%) | .724 |
| CSF Aβ42/Aβ40 ratio, mean (SD), and then t-test | 0.0687 (0.0233) | 0.0734 (0.0226) | .1754 |
| Amyloid pathology, number Aβ+ (% CSF Aβ42/Aβ40 < 0.0673) | 62 (50.82%) | 51 (42.149%) | .1085 |
| AHI, number of respiratory events/h of monitoring time (%) | .1798 | ||
| None (< 5) | 47 (38.525%) | 60 (49.587%) | |
| Mild (5–<15) | 49 (40.164%) | 40 (33.058%) | |
| Moderate (15–<30) | 20 (16.393%) | 18 (14.876%) | |
| Severe (≥ 30) | 6 (4.918%) | 3 (2.479%) | |
| PLMI, number of leg movements/h of monitoring time (%) | .8073 | ||
| None (< 15) | 56 (45.902%) | 65 (53.719%) | |
| Low (15–<45) | 39 (31.967%) | 30 (24.793%) | |
| High (≥ 45) | 27 (22.131%) | 26 (21.488%) | |
| Sleep timing variability, mean (SD) | 0.526 (0.263) | 0.658 (0.405) | .00299 |
SD, standard deviation; CDR, clinical dementia rating; ApoE4 status, apolipoprotein E ε4 positive; CSF, cerebrospinal fluid; Aβ, amyloid-beta; AHI, apnea–hypopnea index; PLMI, periodic limb movement index.
Bold P-values are significant at <0.05.