Light therapy for multiple sclerosis-associated fatigue: a randomized, controlled phase II trial.

Background: Bright white light therapy (LT) can improve fatigue in several disease states but has not been studied in multiple sclerosis (MS).

Objective: To determine whether controlled home-based LT is feasible, tolerable, and well-adhered to in MS-associated fatigue.

Methods: A randomized, controlled trial of twice-daily 1-h bright white LT (BWLT) (10,000 lx, active arm) versus dim red LT (DRLT) (< 300 lx, control arm) was performed. Adults with MS-associated fatigue were enrolled for 10 weeks: 2-week baseline, 4-week intervention, 4-week washout.

Results: 41 participants were enrolled; 35 were randomized (average age 42 years, 80% female; BWLT n = 20; DRLT n = 15). 31 were in the intention to treat analysis. The average duration of LT sessions was similar between groups (BWLT 60.9 min, DRLT 61.5 min, p = 0.70). The most commonly reported adverse event was headache. There were no events that led to discontinuation. Baseline fatigue was severe in both arms (each 53/63 points on the Fatigue Severity Scale (FSS), p = 0.92). FSS was lower following BWLT (FSS 45.8 post-LT, p = 0.04; 44.9 post-washout, p = 0.02 intra-group compared to baseline FSS) and DRLT (FSS 46.7 post-LT, p = 0.03; 43.9 post-washout, p = 0.002 intragroup compared to baseline FSS). There was no difference between BWLT and DRLT groups in the magnitude of reduction of FSS scores (p = 0.81 after LT; p = 0.77 after washout for between group comparisons). Similarly, MS quality of life metrics improved in both arms but were not significantly different between groups after LT (p = 0.22) or washout.

Conclusions: LT is safe, feasible, and well-tolerated in people with MS-associated fatigue. Improvement in both light spectra likely indicates a strong placebo effect for the DRLT group.