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Updated: Jan 29, 2026
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Published on: April 29, 2007
Bright light therapy for depression in Parkinson disease: A randomized controlled trial
Sonja Rutten1, Chris Vriend2, Jan H Smit2
1From Amsterdam UMC (S.R., C.V., J.H.S., E.J.W.v.S., A.W.H., O.A.v.d.H.), Vrije Universiteit Amsterdam, Department of Psychiatry, Amsterdam Neuroscience; Department of Research and Innovation (S.R., J.H.S., A.W.H., O.A.v.d.H.), GGZ InGeest; Amsterdam UMC (C.V., H.W.B., Y.D.v.d.W.), Vrije Universiteit Amsterdam, Department of Anatomy and Neurosciences, Amsterdam Neuroscience; Amsterdam UMC (H.W.B.), Vrije Universiteit Amsterdam, Department of Neurology, Amsterdam Neuroscience; Department of Sleep and Cognition (E.J.W.v.S., Y.D.v.d.W.), Netherlands Institute for Neuroscience; Department of Integrative Neurophysiology (E.J.W.v.S.), Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University; and Amsterdam UMC (J.W.T.), Vrije Universiteit Amsterdam, Department of Epidemiology and Biostatistics, Amsterdam, the Netherlands. s.rutten@vumc.nl.
Objective:
To assess the efficacy of bright light therapy (BLT) in reducing depressive symptoms in patients with Parkinson disease (PD) and major depressive disorder (MDD) compared to a control light.
Methods:
In this double-blind controlled trial, we randomized patients with PD and MDD to treatment with BLT (±10,000 lux) or a control light (±200 lux). Participants were treated for 3 months, followed by a 6-month naturalistic follow-up. The primary outcome of the study was the Hamilton Depression Rating Scale (HDRS) score. Secondary outcomes were objective and subjective sleep measures and salivary melatonin and cortisol concentrations. Assessments were repeated halfway, at the end of treatment, and 1, 3, and 6 months after treatment. Data were analyzed with a linear mixed-model analysis.
Results:
We enrolled 83 participants. HDRS scores decreased in both groups without a significant between-group difference at the end of treatment. Subjective sleep quality improved in both groups, with a larger improvement in the BLT group (B [SE] = 0.32 [0.16], p = 0.04). Total salivary cortisol secretion decreased in the BLT group, while it increased in the control group (B [SE] = -8.11 [3.93], p = 0.04).
Conclusion:
BLT was not more effective in reducing depressive symptoms than a control light. Mood and subjective sleep improved in both groups. BLT was more effective in improving subjective sleep quality than control light, possibly through a BLT-induced decrease in cortisol levels.
Clinicaltrialsgov Identifier:
NCT01604876.
Classification Of Evidence:
This study provides Class I evidence that BLT is not superior to a control light device in reducing depressive symptoms in patients with PD with MDD.
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