Back pain can have causes that aren't due to underlying disease. Examples include overuse such as working out or lifting too much, prolonged sitting and lying down, sleeping in an uncomfortable position, or wearing a poorly fitting backpack.
Short-term effects of bright light therapy in adults with chronic nonspecific back pain: a randomized controlled trial
Conclusion: The present randomized controlled trial shows that light therapy even in low dose could improve depressive symptoms and reduce pain intensity in CNBP patients. Further research is needed for optimizing parameters of frequency, dose, and duration of therapeutic light exposure.