Side effects induced by bright light treatment for seasonal affective disorder

Bright light treatment has become an accepted treatment for seasonal affective disorder (SAD), but there have been few studies about adverse effects from using this treatment. We conducted a study to examine the frequency of adverse effects of bright light treatment for SAD.

Thirty patients meeting DSM-III-R criteria for major depression, recurrent, with seasonal pattern as determined by the Structured Clinical Interview for DSM-III-R were administered a structured interview, the 42-item Systematic Assessment for Treatment Emergent Events, to assess side effects from bright light treatment.

Side effects were limited and mild. They remitted with time or decreased light. No patient discontinued treatment. One patient developed mild hypomania and 3 became agitated. Sleep disturbance occurred in 62% of patients (5 of 8) using evening light. Visual side effects occurred in 26% of patients (8 of 30).

Except for one case of mild hypomania, no other clinically significant treatment-emergent adverse effects developed. Hypomania is an uncommon, but clinically important side effect. Mild visual complaints were common and remitted promptly. In this group of patients with SAD, bright light treatment was well tolerated and resulted in a limited number of adverse effects, none of which compromised treatment. The absence of a control group limits the specificity of these side effects to bright light treatment.