Measures of Sleepiness, Quality, and Quantity of Recent Sleep and Risk of Injury
| Case-Crossover Analyses | Case-Control Analyses | |
|---|---|---|
| Self-perceived sleepiness at injury or matched time | ||
| Per unit on a 0-to-12 scale | 0.78 (0.75 to 0.81) | 0.74 (0.72 to 0.77) |
| Dichotomous: >0 vs 0 | 0.47 (0.39 to 0.55) | 0.27 (0.23 to 0.33) |
| Trichotomous: 1 to 3 vs 0 | 0.60 (0.50 to 0.72) | 0.48 (0.39 to 0.59) |
| 4 to 12 vs 0 | 0.24 (0.18 to 0.30) | 0.14 (0.11 to 0.17) |
| Usual Sleep | ||
| Quality (per point on a 5-point ordinal scale) | Because these variables address longer-term constructs, only case-control analyses are possible. | 1.04 (0.98 to 1.10) |
| Quantity (per hour) | 0.98 (0.94 to 1.03) | |
| Quantity in past 7 days compared with your usual (per point on a 5-point ordinal scale) | 0.97 (0.90 to 1.05) | |
| Quality in past 7 days compared with your usual (per point on a 5-point ordinal scale) | 0.88 (0.80 to 0.97) | |
| Sleep in past 48 hours | ||
| Sleep in past 24 hours compared with the 24 hours before that, per hour | 1.06 (1.03 to 1.09) | Data not available from control group. |
| Last episode of sleep compared with the previous one, per hour | 1.01 (0.98 to 1.04) | |
| Trichotomous, past 24 hours compared with previous 24 hours | ||
| Less than 5 hours compared with 5 to 9 hours | 0.88 (0.68 to 1.13) | |
| 10 hours or more compared with 5 to 9 hours | 1.28 (1.07 to 1.55) | |
| Sleep in past 24 hours compared with usual quantity (per hour) | 1.29 (1.24 to 1.34) |
ORs (95% CI).