Light Therapy for Depression
Authored by:
Anna Glezer, M.D.
Perinatal and postpartum depression affects many women, by some studies up to 10-20%. In my clinical practice, I also have many women who struggle with the decision about taking medications for treatment of this condition given the potential for side effects and exposure to the baby. Therefore, there is always a search for non-pharmacologic treatment options. Light therapy is one such option.
What is Light therapy?
Bright light therapy involves exposure to a lamp of 5,000 -10,000 lux, usually for at least 10-60 minutes per day in the early morning. One benefit of light therapy is that it can be done at home! Unlike psychotherapy, which often requires arranging childcare and scheduling limitations, this is done on one’s own schedule. Another benefit is the lack of significant side effects – most commonly these are some eye strain or headache.
Bright light therapy has been best studied for treating seasonal affective disorder – a syndrome of depression that hits during the long, dark winter months. Though it has also been shown to be effective for other forms of depression as well and other conditions related to disturbed sleep, such as jet-lag or shift work. Because of this success, it has begun to be studied in pregnant and postpartum women.
How does Bright Light Therapy work?
Several theories explain why pregnant and postpartum women might respond well to this treatment. The first is the logistics of pregnancy and the postpartum period. Whether due to bedrest, fatigue, sleep deprivation, or the difficulty of getting outside with a newborn, many moms spend many hours indoors, decreasing their natural exposure to daylight. This, in turn, can change a woman’s circadian rhythm and the production of melatonin, the hormone responsible for our sleep-wake cycle.
Second, bright light affects a woman’s serotonergic system and estrogen levels. Serotonin is the neurochemical known to regulate mood and anxiety, and is the target of many antidepressant and antianxiety medications. Estrogen levels are dynamic throughout pregnancy and postpartum. There is some very early evidence that bright light stimulates the gonadotropin (luteinizing hormone) which is responsible for estrogen production.
Finally, sleep disturbance is a significant part of pregnancy and postpartum (SEE: Sleep Article). Sleep debt causes changes in our circadian rhythms. Bright light therapy has been helpful in conditions of circadian rhythm dysregulation, from dementia to jet lag.
Is it effective for perinatal and postpartum depression?
A few small early studies provide promising results, noting improvement in mood, as measured by rating scales, in as little as 3-5 weeks after consistent use of a bright light lamp. One caveat of these early studies is that they are quite small (sometimes as few as 10 participants) and often use self-report to determine adherence to the light schedule.
Another element to consider is that committing to bright light therapy means committing to at least half an hour of quiet morning time. Many postpartum women rarely have that kind of time to themselves, and that alone could help contribute to improvement in symptoms.
Who should consider Bright Light Therapy?
Women who are pregnant or postpartum and struggling with mild to moderate symptoms of depression may be good candidates for Bright Light Therapy, particularly if there is a reluctance to consider medication management (which might be for a myriad of reasons, including side effects). It allows for a comfortable in-home treatment option with the initial investment in the purchase of a lamp. It is also a treatment option to consider for women who may need to augment their current psychotherapy or psychopharmacologic treatment with another method for full relief of symptoms.
References:
Crowley, SK, & Youngstedt, SD. Efficacy of light therapy for perinatal depression: A review. (2012) Journal of Physiological Anthropology 31:15.
