The primary objective of this study is to evaluate the effect of light therapy using a narrow 467nm light compared to a 580nm light in subjects with Seasonal Affective Disorder (SAD). It is hypothesized that the 467nm light will improve the symptoms of SAD better than the 580nm light.

Participants will be randomly assigned to receive either a 467nm light or a 580nm light. Participants will use the light every day for six weeks for 30 minutes. Multiple assessments and questionnaires will be given weekly to assess the efficacy of the treatment.

Inclusion Criteria:

1. Males and females, ages 21-64

2. Able and willing to provide written informed consent

3. History of recurrent major depressive episodes with winter-type seasonal pattern by Diagnostic and Statistical Manual of the American Psychiatric Associated, 4th Ed. (DSM-IV) criteria (American Psychiatric Association, 1990), based on diagnostic interview utilizing the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) (First et al., 2007)

   *Bipolar I excluded for this study

4. SIGH-ADS score of ≥20

5. Use of the light device as instructed by the study clinician for at least 6 out of 7 days for the first two weeks of therapy and at least 5 out of 7 days for the remaining four weeks of therapy.

Exclusion Criteria:

1. Participation in a study of investigational or marketed drugs or devices during the 30-day period prior to the start of the study or during the study
2. Subjects who are medically complicated, medically unstable and/or have other severe diseases, as determined by the investigator.
3. Abnormal TSH level, (outside range of 0.3 to 5.0 mlU/L), as determined by the TSH levels blood test
4. History of concurrent psychiatric illness that would preclude compliance with the protocol and/or ability to complete the study safely
5. History or current diagnosis of Bipolar I Disorder
6. Variable psychiatric symptoms such as rapid cycling or severe premenstrual syndrome that could interfere with accurate assessment of the treatment effect
7. History of a medical condition that affects mood or produces hallmark symptoms of a mood disorder (i.e. hypothyroidism)
8. History of current or recent (within previous 12 months) alcohol, narcotic or other drug abuse by DSM-IV criteria
9. Positive urine drug screen at the Physical Screening
10. Active suicidal or homicidal ideation or plan, as determined by the investigator
11. Global Assessment of Functioning (GAF) <51 (see Appendix B)
12. Use of light therapy treatment within the previous 6 months or any history of goLITE use
13. Pregnant or lactating (will confirm absence of pregnancy with a urine or serum pregnancy test in females of childbearing potential during the Physical Screening. Additional pregnancy tests may be performed as per individual site requirements). Females of child-bearing potential must agree to use some form of birth control throughout the course
14. Current use or use within 2 months of antidepressants or mood stabilizing medications, even if taken for a non-psychiatric indication
15. Currently working night shift or rotating shift or other habitual alteration of the sleep/wake cycle
16. Planned travel outside of the state in which the trial is being conducted
17. Current use or use within the previous 1 month of photosensitizing medications (amiodarone, benoxaprofen, chlorpromazine, demeclocycline, fleroxacin, nalidixic acid, ofloxacin, piroxicam, porfimer, psoralens, quinidine, temoporfin) or remedies (St. John's wort, melatonin)
18. History of eye trauma or disease, retinopathy, and/or cataract of a level that would significantly affect transmission or processing of light through either eye
19. Ishihara score of <10 on the Ishihara Test for Color Deficiency
20. Use of medications, such as tetracycline or oral isoretinoin (Accutane), that would affect the safety of light exposure treatment or that causes complaints of eyestrain or abnormal tearing with computer use of up to 30 minutes at a time

6 weeks