Table 2. Effects of LT on Parkinson Disease Severity, Sleep, Alertness, Depression, Fatigue, and Quality of Life.
| Outcome 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 | |||
| UPDRS | 39.69 (15.85) | 45.07 (20.15) | 35.47 (17.67) | 40.02 (19.48) | .39/.001 | 35.94 (12.29) | 40.20 (18.68) | .43/.78 |
| I | 1.75 (0.86) | 2.27 (1.49) | 1.40 (1.06) | 1.33 (1.18) | .49/.008 | 1.56 (1.41) | 1.87 (1.36) | .74/.07 |
| II | 10.44 (5.23) | 10.40 (7.13) | 8.87 (4.87) | 9.53 (6.39) | .84/.03 | 10.13 (4.30) | 10.40 (6.66) | .79/.02 |
| III | 24.75 (11.26) | 29.13 (12.43) | 22.67 (13.12) | 25.87 (11.87) | .35/.01 | 21.94 (8.84) | 24.60 (11.79) | .44/.52 |
| IV | 2.75 (2.24) | 3.27 (2.12) | 2.53 (1.85) | 3.47 (2.67) | .33/.80 | 2.31 (1.85) | 3.33 (2.64) | .22/.47 |
| BDI | 8.31 (3.63) | 8.27 (4.71) | 7.88 (4.53) | 9.33 (10.57) | .84/.26 | 7.06 (5.56) | 10.40 (10.49) | .94/.73 |
| ESS | 15.81 (3.10) | 15.47 (2.59) | 11.19 (3.31) | 13.67 (4.78) | .37/<.001/.005 | 11.38 (4.15) | 13.13 (3.56) | .10/.81 |
| PSQI | 7.88 (4.11) | 8.87 (2.83) | 6.25 (4.27) | 7.33 (3.52) | .40/.006 | 5.56 (3.60) | 6.00 (2.39) | .51/.08 |
| PDSS | 97.24 (22.49) | 95.11 (19.86) | 106.98 (19.37) | 99.28 (16.94) | .4792/.001 | 103.23 (21.76) | 100.49 (17.87) | .43/.53 |
| FSS | 41.62 (12.62) | 37.00 (9.10) | 37.92 (13.65) | 36.53 (11.54) | .57/.48 | 37.07 (13.01) | 39.21 (10.39) | .94/.63 |
| PDQ-39 | 41.46 (19.30) | 36.80 (19.72) | 43.00 (14.84) | 39.40 (26.17) | .49/.41 | 41.00 (18.68) | 37.20 (27.38) | .64/.23 |
Abbreviations: BDI, Beck Depression Inventory; ESS, Epworth Sleepiness Scale; FSS, Fatigue Severity Scale; LT, light therapy; PDQ-39, Parkinson’s Disease Questionnaire (39-item); PDSS, Parkinson’s Disease Sleep Scale; PSQI, Pittsburgh Sleep Quality Index; UPDRS, Unified Parkinson’s Disease Rating Scale.
For the BDI, a score of 0 to 13 indicates minimal depression; 14 to 19, mild depression; 20 to 28, moderate depression; and 29 to 63, severe depression. For the ESS, a score equal to or greater than 10 is considered indicative of excessive daytime sleepiness. For the PSQI, a global PSQI score equal to or greater than 5 indicates poor sleep quality. For the PDSS, a higher score indicates better sleep. For the UPDRS, a higher score indicates more severe disease. For the FSS, a total score greater than 36 is indicative of fatigue.