Cancer related fatigue (CRF) is one of the most prevalent and distressing long-term complaints reported by (non-) Hodgkin survivors. To date there has been no standard treatment for CRF in this population. A novel and promising approach to treat CRF is exposure to bright white light therapy | Light therapy as a treatment of cancerrelated fatigue in non- Hodgkin lymphoma survivors SPARKLE trial Study protocol of a multicenter randomized controlled trial