Table 1.
Average sleep and mood parameters by participant across placebo and caffeine conditions.
| S33 | S84 | S85 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No treatment | Placebo | Caffeine | p | No treatment | Caffeine | p | No treatment | Placebo | Caffeine | p | |
| Sleep onset (hh:mm) | 23:08 ± 00:50 | 23:10 ± 00:30 | 23:01 ± 00:35 | 0.14 | 23:42 ± 00:39 | 23:53 ± 01:04 | 0.89 | 23:26 ± 00:57 | 23:10 ± 00:46 | 23:01 ± 00:47 | 0.07 |
| Sleep latency (min) | 1.63 ± 2.91 | 1.61 ± 3.64 | 0.13 ± 0.80 | 0.007 | 16.86 ± 15.77 | 35.36 ± 61.57 | 0.01 | 15.53 ± 8.36 | 15.39 ± 6.08 | 11.81 ± 2.44 | 0.02 |
| Sleep offset (hh:mm) | 05:36 ± 01:11 | 06:03 ± 01:09 | 05:49 ± 00:59 | 0.03 | 05:52 ± 01:12 | 05:57 ± 01:36 | 0.07 | 04:54 ± 01:21 | 05:06 ± 01:27 | 04:52 ± 01:29 | 0.63 |
| WASO (number/night) | 0.92 ± 1.13 | 1.02 ± 1.04 | 0.69 ± 0.77 | 0.37 | 3.46 ± 1.08 | 3.12 ± 1.27 | 0.11 | 0.82 ± 0.73 | 0.97 ± 0.74 | 1.36 ± 0.84 | 0.005 |
| WASO duration (min) | 14.98 ± 39.78 | 9.27 ± 38.69 | 9.74 ± 21.97 | 0.33 | 179.24 ± 69.13 | 208.06 ± 89.60 | 0.07 | 19.16 ± 32.66 | 28.03 ± 34.45 | 33.49 ± 29.98 | 0.006 |
| Sleep quality | 1.65 ± 1.63 | 1.49 ± 1.40 | 1.28 ± 1.00 | 0.48 | 6.93 ± 1.14 | 7.06 ± 1.17 | 0.74 | 3.44 ± 1.12 | 3.03 ± 0.87 | 3.15 ± 0.81 | 0.17 |
| Nighttime sleep duration (min/night) | 372.73 ± 64.73 | 403.83 ± 68.76 | 398.97 ± 64.11 | 0.02 | 352.38 ± 74.19 | 336.25 ± 117.97 | 0.80 | 308.55 ± 83.90 | 328.41 ± 88.71 | 317.62 ± 78.16 | 0.56 |
| Naps (number/day) | 0.08 ± 0.35 | 0.10 ± 0.30 | 0.00 ± 0.00 | 0.16 | 1.64 ± 1.43 | 2.13 ± 1.95 | 0.21 | 0.47 ± 0.58 | 0.32 ± 0.47 | 0.28 ± 0.46 | 0.26 |
| Nap duration (min) | 2.98 ± 12.50 | 7.32 ± 23.98 | 0.00 ± 0.00 | 0.15 | 25.35 ± 23.02 | 39.16 ± 35.33 | 0.05 | 41.94 ± 60.46 | 27.59 ± 45.11 | 27.18 ± 48.03 | 0.35 |
| 24-h sleep duration (min/24 h) | 368.96 ± 85.14 | 411.15 ± 72.93 | 398.97 ± 64.11 | 0.02 | 382.07 ± 71.85 | 376.31 ± 115.33 | 0.61 | 352.53 ± 82.23 | 356.00 ± 66.64 | 344.79 ± 78.69 | 0.91 |
| Alert (1)–Sleepy (9) | 1.51 ± 0.51 | 1.39 ± 0.63 | 1.09 ± 0.29 | <0.0001 | 5.84 ± 1.78 | 5.52 ± 1.94 | 0.14 | 3.72 ± 1.62 | 3.64 ± 1.38 | 3.36 ± 1.07 | 0.53 |
| Cheerful (1)–Miserable (9) | 1.12 ± 0.33 | 1.17 ± 0.51 | 1.00 ± 0.00 | 0.04 | 5.01 ± 1.33 | 4.91 ± 1.34 | 0.42 | 2.75 ± 0.66 | 2.80 ± 0.52 | 2.72 ± 0.57 | 0.31 |
| Calm (1)–Tense (9) | 1.00 ± 0.00 | 1.05 ± 0.21 | 1.00 ± 0.00 | 0.13 | 4.40 ± 1.61 | 3.92 ± 1.36 | 0.003 | 2.65 ± 0.48 | 2.79 ± 0.41 | 2.85 ± 0.36 | 0.008 |
| Depressed (1)–Elated (9) | 5.00 ± 0.00 | 5.00 ± 0.00 | 5.00 ± 0.00 | 1.00 | 4.71 ± 0.89 | 4.83 ± 0.81 | 0.14 | 5.07 ± 0.33 | 5.00 ± 0.00 | 5.00 ± 0.00 | 0.03 |