Essential Reads: Bright Light Therapy for the Treatment of Depression During Pregnancy, Mixed Findings

Despite data to support the reproductive safety of many antidepressants during pregnancy, many women would prefer to avoid medications, if possible.  In this setting, many women pursue psychotherapy, others use acupuncture or yoga or exercise. Although non-pharmacologic treatments are perceived as being safer than medications, this is only true if the treatment is effective.  Exposure to untreated psychiatric illness in the mother carries is not without risk and has been associated with worse outcomes.

Bright light therapy may be an attractive treatment for perinatal depression because it is inexpensive, can be performed at home, and carries a low risk of side effects.   Most importantly, there is evidence to support the efficacy of bright light for both seasonal and non-seasonal types of depression.  

Light Therapy for Depression During Pregnancy

In an open trial including 16 pregnant women with a major depressive episode, Oren and colleagues (2002, reviewed HERE) showed a significant decrease (by 49%) from baseline in Hamilton Depression Rating Scale (HDRS), Seasonal Affective Disorders Version (SIGH-SAD) scores after 3 weeks of 10,000 lux bright light therapy. Light was administered for 60 minutes per day, beginning within 10 minutes of awakening. In a subset of participants (n?=?7) who continued treatment for 5 weeks, scores on the SIGH-SAD decreased even further, falling 59% from baseline. 

Epperson and colleagues (2004) conducted a randomized controlled trial in which participants with antepartum depression received either 7,000 lux (active, n=5) or 500 lux (placebo, n=5) of light for 5 weeks. The treatments were administered for 60 minutes per day, beginning within 10 minutes of awakening.  There were no differences between the treatment and placebo groups at 5 weeks.  SIGH-SAD scores were reduced similarly by bright light and by dimmer light; however, when the treatment was extended to ten weeks, they did observe a greater reduction in depressive symptoms in women receiving active treatment versus placebo.  

In another randomized, placebo-controlled trial (reviewed HERE), Wirz-Justice and colleagues assigned women with antenatal depression to receive either 7,000 lux white light (n=24) or placebo (n=22, 70 lux red or dim light) which were administered for 60 minutes daily for 5 weeks.   Participants receiving the bright light treatment showed significantly greater improvement in HDRS with Atypical Depression Supplement (SIGH-ADS) scores than those in the placebo treatment, and categorical analysis revealed that the response rate (at least 50% improvement in HDRS score) at week 5 was significantly greater for bright light (81.3%) than for placebo (45.5%). Remission (HDRS < 8 ) was attained by 68.6% in the light group versus 36.4% in the placebo group (p < .05).

The most recent clinical trial (Bais et al, 2020), however, yielded different results.  In this study, 67 pregnant women (12-32 weeks gestational age) meeting criteria for a DSM-5 diagnosis of a major depressive episode were randomly assigned to receive treatment with either bright light therapy (BLT, 9000 lux, 5000 K) or placebo dim red light therapy (DRLT, 100 lux, 2700 K). For 6 weeks, both groups were treated daily at home for 30 minutes on awakening.  Assessments took place weekly during the intervention, at 3 and 10 weeks post-treatment and at 2 months postpartum.

In this study, median depression scores decreased by 40.6%-53.1% in the BLT group and by 50.9%-66.7% in the DRLT group.  There were no statistically significant differences in symptom change scores between BLT and DRLT groups.   This study differed from the trials of Epperson et al and Wirz-Justice et al in that these earlier studies used one hour a day administered within 10 minutes of waking, instead of the 30 minutes used in the Bais trial.

Is Bright Light Therapy a Viable Option?

In terms of efficacy, the jury is still out.  However, if there is a patient who has responded well to bright light therapy in the past, one may consider this option during pregnancy.  Further research is necessary to determine who is most likely to benefit from this intervention.

Risks to the fetus: No studies have assessed the risk of light therapy to the fetus; however, because one hour of light therapy provides the same amount of  light exposure to one hour of outdoor daylight, this treatment should not pose any risk to the fetus.  

Side effects: In terms of side effects, light therapy is generally well-tolerated.  Side effects include eyestrain, headache, and nausea.  For patients with bipolar disorder, light therapy may trigger hypomania or mania.

One of the real challenges with bright light therapy is adherence.  The studies outlined above required one hour of light exposure per day for 5-10 weeks.  Its effectiveness depends on three factors: light intensity, duration of the session, and timing.

  • Intensity: The typical recommendation is to use a 10,000-lux light box at a distance of about 16 to 24 inches from the face.  
  • Duration. With a 10,000-lux light box, light therapy typically involves daily sessions of about 20 to 30 minutes. However, the studies for perinatal depression above used one hour sessions of 7,000 or 10,000 lux.
  • Timing. Light therapy is most effective when performed early in the morning, shortly after waking. 
  • Length of Treatment: Most studies have used 6 weeks, Epperson et al observed benefit only after 10 weeks of treatment

While light therapy may not be a replacement for antidepressant medications for all pregnant women with depression, light therapy could play an important role in the treatment of certain subgroups of women.  Because patients with more severe depression (i.e., those with suicidal ideation and/or psychotic symptoms) were excluded from these studies, it is unclear if light therapy would be effective in this population.  Similarly it is not known if light therapy would be as effective for women with comorbid anxiety disorders.

Ruta Nonacs, MD PhD

Bais B, Kamperman AM, Bijma HH, Hoogendijk WJ, Souman JL, Knijff E, Lambregtse-van den Berg MP.  Effects of bright light therapy for depression during pregnancy: a randomised, double-blind controlled trial.  BMJ Open. 2020 Oct 28;10(10):e038030. Free article. 

Epperson CN, Terman M, Terman JS, Hanusa BH, Oren DA, Peindl KS, Wisner KL.  Randomized clinical trial of bright light therapy for antepartum depression: preliminary findings.  J Clin Psychiatry. 2004 Mar;65(3):421-5. 

Oren DA, Wisner KL, Spinelli M, Epperson CN, Peindl KS, Terman JS, Terman M: An open trial of morning light therapy for treatment of antepartum depression. Am J Psychiatry. 2002, 159: 666-669.

Smith CA, Shewamene Z, Galbally M, Schmied V, Dahlen H.  The effect of complementary medicines and therapies on maternal anxiety and depression in pregnancy: A systematic review and meta-analysis.  J Affect Disord. 2019 Feb 15; 245:428-439.

Wirz-Justice A, Bader A, Frisch U, et al. A Randomized, Double-Blind, Placebo-Controlled Study of Light Therapy for Antepartum Depression. J Clin Psychiatry 2011; 72(7):986-993.

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