 2. Light treatment. Safety of equipment. Light therapy with bright fluorescent light has been tested in many individuals and serious irreversible adverse effects have not been reported. The most common side effect of light therapy is irritability or agitation that remits after termination of the light or decrease of the daily duration of exposure. Participants will be carefully monitored for such side effects and light therapy exposure will be decreased or eliminated if these adverse effects occur. Although light treatment has been tested in pregnant women in a small number of studies, the safety of light treatment in pregnant women has not been conclusively established. Female subjects will be told that participation in this study may be hazardous to an embryo or fetus and therefore that it is essential that adequate birth control be used while participating. If they should become pregnant while in the study, they should notify the investigators immediately. 