BLT for BD: What’s the evidence?
Several studies and case reports have evaluated the use of BLT for bipolar depression. The number of participants in these studies is small, and there is no uniformity of methodology or patient selection.
Dauphinais et al (2012)25 randomly assigned 44 patients with bipolar depression to BLT or a high-density or low-density negative ion generator for 8 weeks. They reported no difference in outcome between the various groups (50% vs 55.6%, remission and response rate). Only one patient in each group showed a switch to hypomania.
Carmadese et al (2015)26 reported an open-label study of adjunctive BLT in 31 difficult-to-treat patients with depression (16 unipolar and 15 bipolar). Significant improvement was noted within 3 weeks and was sustained in 1 patient with bipolar depression 5 weeks after cessation of BLT.
Papatheodorou and Kutcher (1995)27 treated 7 adolescents with bipolar depression with adjunctive BLT (10,000 lux twice per day). Three patients showed a marked response (>70% decrease from baseline Beck Depression Inventory and Symptom Check List scores). Two patients had a moderate response (40% to 47% decrease) and 2 patients obtained mild to no response. There were no reported adverse effects.
Benedetti et al (2014)28 studied 141 patients with treatment-resistant bipolar depression. Approximately one-quarter (23%) had a history of attempted suicide, and 83% had a history of drug resistance. The authors found a combination of total sleep deprivation, BLT, and lithium rapidly decreased suicidality and improved patients’ depressive symptoms.
Liebenluft et al (1995)29 administered 13 trials of BLT to 9 patients with rapid-cycling BD during a 3-month period. Five patients received the treatment in the morning, 5 around midday, and 3 in the evening. Patients who received BLT at midday had the best outcome, while 3 of the 5 patients who received morning BLT developed unstable mood. The authors recommended titrating the duration of light exposure so that patients could skip a treatment if their mood was trending toward hypomania.
Sit et al (2007)30 evaluated BLT in a case series of 9 women with bipolar I or II disorder in the depression phase. Patients were exposed to 50 lux of red light for 2 weeks, and then they received 7,000 lux BLT for 15, 30, and 45 minutes daily for 2 weeks (4 patients received morning light and 5 received midday light). Mood was assessed using the Structured Interview Guide for the Hamilton Depression Rating Scale with Atypical Depression Supplement and the Mania Rating Scale. Of the 4 patients receiving morning BLT, one patient had a full response and the other 3 developed hypomania. Of the 5 patients who received midday BLT, 2 achieved full response, 2 showed early improvement but required a dose increase, and one remained depressed but had a full response when she was switched to morning BLT.
Tseng et al (2016)31 reported a meta-analysis of BLT for bipolar depression that included a total of 567 patients from 11 studies. They reported significant improvement with BLT alone or in combination with antidepressants or total sleep deprivation. They also reported significant improvement with BLT in 130 patients who were not receiving other treatments. There was no difference in the frequency of mood shifts between patients on BLT alone or in combination with other modalities. The authors reported no mood shift in any of the patients receiving concurrent mood stabilizers. They also reported no difference with the color of light, gender, or duration of illness.
Yorguner et al (2017)32 conducted a 2-week randomized, single-blind study of BLT as an add-on treatment for 32 patients with bipolar depression. Patients were randomly assigned to BLT or dim light, which they were administered each morning for 30 mins for 2 weeks. Sixteen patients who received BLT showed a significantly greater reduction in Hamilton Depression Rating Scale scores (mean score of 24 at baseline down to 12) compared with 16 patients who received dim light (mean score of 24 at baseline down to 18). The authors also reported remission in 4 out of 4 patients who had seasonal depression, compared with 3 out of 12 who did not have seasonal depression (the other 9 showed response but not remission).
Zhou et al (2018)33 conducted a multi-center, randomized, single-blind clinical trial of 63 patients with bipolar depression. Thirty-three patients received morning BLT, and 30 received dim red light therapy (control group). The authors reported a significantly higher response rate in the BLT group (78%) compared with the control group (43%).
Sit et al (2018)34 conducted a 6-week randomized, double-blind, placebo-controlled trial of BLT vs dim red light in patients with bipolar I or II depression. Twenty-three patients were administered 7,000 lux bright white light, and 23 patients received 50 lux dim red light, at midday 5 days a week. The light dose was increased by 15 minutes every week up to 60 minutes by Week 4, unless the patient achieved remission. Patients were maintained on their usual medications, which included mood stabilizers and/or antidepressants. At Week 6, the group randomized to BLT had a significantly higher remission rate (68%) compared with patients who received dim red light (22%). Improvement was noted by Week 4. Patients receiving BLT also had significantly fewer depressive symptoms, and no mood polarity switch was noted.