By contrast, bright light therapy is used during waking hours. The maximum light intensity is around 400 lux. By contrast, bright light therapy requires scheduling waking hours for treatment. Although DDS therapy appears advantageous, there have been far fewer clinical trials using this method.
Case studies using a combination of dusk and dawn signals are very promising.
The dusk twilight fade is scheduled around bedtime, and the dawn reaches its peak around wake-up time. Apparatus for DDS delivery varies widely in design and adherence to the outdoor naturalistic pattern. DDS controllers are sometimes provided without lamps, and sometimes combined with lamps. Choice of lamp and fixture is important, with the goal of bathing the sleeping area in a diffuse light signal that will reach the eyes regardless of sleeping posture. The initial demonstration of DDS therapy was by Drs.