Table 3. Effects of LT on Self-reported Sleep Diaries.
| Sleep Diary Measurea | Mean (SD) |
P Value, Group/ Condition/ Interaction |
||||||
|---|---|---|---|---|---|---|---|---|
| Baseline | Postintervention (Week 4) |
P Value, Group/ Condition/ Interaction |
Postwashout (Week 6) | |||||
| Bright LT | Dim-Red LT | Bright LT | Dim-Red LT | Bright LT | Dim-Red LT | |||
| Sleep | ||||||||
| Duration, h | 7.42 (0.99) | 7.43 (1.31) | 6.95 (0.95) | 7.25 (1.29) | .71/.05 | 7.03 (0.90) | 7.35 (1.29) | .43/.59 |
| Latency, min | 37 (45) | 24 (16) | 23 (21) | 22 (10) | .42/.02 | 20 (16) | 24 (12) | .65/.64 |
| No. of awakenings | 1.51 (1.03) | 2.18 (1.09) | 0.92 (0.97) | 1.77 (1.08) | .02/<.001/.006 | 1.28 (1.13) | 1.76 (1.02) | .03/.01/.004 |
| Wake during night, min | 45.18 (50.63) | 38.56 (21.69) | 39.74 (40.93) | 31.77 (23.28) | .54/.05 | 40.19 (48.46) | 29.53 (19.62) | .44/.89 |
| Sleep quality | 3.03 (1.01) | 3.58 (0.53) | 3.53 (0.91) | 3.61 (0.75) | .38/<.001/.002 | 3.47 (0.82) | 3.79 (0.43) | .54/.73 |
| Feeling refreshed | 2.93 (0.84) | 3.39 (0.77) | 3.03 (1.15) | 3.44 (0.95) | .24/.053 | 3.14 (1.00) | 3.65 (0.70) | .22/.08 |
| Easily waking up | 2.42 (0.65) | 2.33 (1.28) | 2.35 (0.62) | 2.32 (1.17) | .74/.59 | 2.45 (0.88) | 2.26 (1.14) | .69/.56 |
| Easily falling asleep | 2.32 (0.89) | 2.65 (1.11) | 1.83 (0.88) | 2.49 (1.10) | .18/<.001/<.001 | 1.85 (0.82) | 2.58 (1.10) | .05/.33 |
| Dreaming | 1.79 (0.78) | 1.83 (0.74) | 1.71 (0.70) | 1.74 (0.65) | .89/.24 | 1.81 (0.80) | 1.63 (0.62) | .91/.66 |
Abbreviation: LT, light therapy.
a
For the 5 sleep measures, scores range from 1 to 5. For the sleep quality and feeling refreshed measures, higher scores are better; for the easily waking up and easily falling asleep measures, lower scores are better; and for the dreaming measure, lower scores indicate less dreaming.