Bright light therapy may be an effective adjunctive treatment even for those with non-seasonal depressive disorders, according to a review of 11 studies.

So far, bright light therapy has been established as an effective adjunctive therapy only among patients of seasonal depressive disorders. 

Whether those with non-seasonal depressive disorders may also benefit has not been established from previous meta-analyses.

However, the researchers argued in JAMA Psychiatry that previous reviews had dealt with small sample sizes and a limited set of statistical analyses.