Table 1.
Questions “Do you usually feel at your best at these times…” asked for each hour of the day and scored: definitely yes = 100; yes = 75; Mixed, undecided = 50; no = 25; and definitely no = 0.
| Variable | Mean | Std. Dev. | Cases |
|---|---|---|---|
| 5 a.m. | 18.8 | 24.6 | 190 |
| 6 a.m. | 20.5 | 24.7 | 189 |
| 7 a.m. | 26.6 | 28.5 | 187 |
| 8 a.m. | 36.6 | 31.8* | 192 |
| 9 a.m. | 50.9 | 31.8* | 192 |
| 10 a.m. | 63.3 | 29.0* | 194 |
| 11 a.m. | 69.1 | 25.4 | 191 |
| 12 noon | 71.7 | 24.9 | 191 |
| 1 p.m. | 73.2 | 24.1 | 191 |
| 2 p.m. | 71.5 | 24.1 | 191 |
| 3 p.m. | 70.6 | 24.9 | 189 |
| 4 p.m. | 70.9 | 25.0 | 191 |
| 5 p.m. | 71.3 | 24.5 | 190 |
| 6 p.m. | 71.6 | 23.5 | 191 |
| 7 p.m. | 74.0 | 22.8 | 191 |
| 8 p.m. | 73.9 | 23.0 | 190 |
| 9 p.m. | 73.0 | 24.2 | 189 |
| 10 p.m. | 67.2 | 27.6 | 190 |
| 11 p.m. | 55.6 | 29.5* | 188 |
| 12 midnight | 46.5 | 30.0* | 188 |
| 1 a.m. | 36.8 | 29.3* | 188 |
| 2 a.m. | 30.2 | 28.0 | 188 |
| 3 a.m. | 22.5 | 23.7 | 189 |
| 4 a.m. | 21.0 | 23.9 | 189 |
Means and standard deviations. US undergraduates. See Figure 1. Nine to five working day highlighted in bold.
*
Significantly different from the average of the standard deviations at p < 0.05 (Chi-square test).