When you suffer from bipolar disorder, life may seem like it’s all about sleep. It’s no longer an apple a day, but rather a full night’s rest that keeps the doctor away. Sure, a single night of poor sleep may just leave you feeling lousy, but when one bad night succeeds another, anxiety starts to build as you wonder if this is the start of another attack. Bipolar patients understand better than any that sleep disturbances can not only predict but also provoke manic episodes (Plante DT & Winkelman JW, Am J Psychiatry 2008;165(7):830–843; Bauer M et al, Psycho Med 2008;38:1069–1071). They recognize that good sleep hygiene and daily routines are essential components of their overall treatment (St-Amand J et al, J Affect Disord 2012; online ahead of print). Good sleep hygiene is especially important for adolescent patients, as this age group is well known for having erratic sleep schedules.
What bipolar patients, as well as their doctors, may not know is the amount of current research centered on light-dark therapy and the potential implications of this research on treating bipolar. The past decade has been filled with studies describing retinal ganglion cells and their role in regulating circadian rhythm (Brainard GC et al, J Neurosci 2001;21:6405–6412; Thapan K et al, J Physiol 2001;535:261–267). These newly discovered receptors in the eye are part of a complex system that senses light and transmits signals to the suprachiasmatic nucleus in the hypothalamus (Gooley JJ et al, Neurosci 2003;23:7093–7106). When functioning properly, the end result is a sleep/wake cycle that works in harmony with the solar cycle of the earth. When stimulated inappropriately (like at night), this system suppresses our pineal gland from releasing melatonin, ultimately resulting in poorer sleep habits (Brainard op.cit).
Additional studies have shown preferential stimulation of these recep-tors by blue light (Vandewalle et al, PLoS One 2007;2(11):e1247; Wright HR & Lack LC, Chronobiol Int 2001;18(5):801–808), which is emitted from our televisions and artificial light sources. The culmination of the research seems to suggest two methods for stimulating sleep: either enforce complete darkness in the hours prior to bed, or create a “physiologic darkness” by somehow blocking out blue light waves.
For most people, the idea of enforcing complete darkness two to three hours before bed seems impractical. Fortunately, it’s been suggested that amber lenses can be worn to block blue light from activating the retinal ganglion cells in our eyes (Phelps J, Med Hypotheses 2008;70:224–229). Theoretically, glasses are worn for a couple hours before bedtime, blocking out all blue light emissions from the TV, lamps, etc, allowing the brain’s production of melatonin to continue uninhibited. Even better, a pair of amber lenses can be picked up for as little as $7 and have a significantly better side effect profile than pharmaceuticals (see http://bit.ly/VzNxxp). Early studies were promising, showing melatonin levels actually increase with amber lenses compared to control (Sasseville A et al, J Pineal Res 2006;41(1):73–78).
More recently, Burkhart and Phelps conducted a small randomized study to assess whether blocking blue light actually leads to a clinical improvement in sleep. The study started with 20 participants who had symptoms of insomnia defined as difficulty falling asleep or staying asleep, or waking earlier than desired. Exclusion criteria included prescription medication use, nicotine, excessive alcohol or caffeine use, and prior knowledge of amber lenses. Ten subjects were assigned to the amber lens group and another 10 to a control group using yellow lenses (which do not effectively block blue wavelengths). The study lasted three weeks; one to establish baseline sleep and mood followed by two weeks of using lenses three hours prior to bedtime. All participants kept sleep diaries and performed daily PANAS mood scales. Although results were subjective and lacked compliance checks, their study showed significant improvement in both sleep and mood for patients wearing amber lenses (Burkhart K & Phelps J, Chronobiol Int 2009;26(8):1602–1612).
Another interesting branch of therapy involves the use of darkness. Research on patients with bipolar disorder who were treated with darkness therapy is limited, but in two case reports of bipolar patients and one of a schizoaffective patient, short-term darkness therapy helped stabilize mood. In a small study of 32 patients with bipolar disorder who were treated on an inpatient unit, half received darkness therapy in the form of 14 hours of enforced darkness per day for three days. The other half received treatment as usual. The study found that scores of the Young Mania Rating Scale decreased more quickly in patients who received the darkness therapy, provided the onset of mania was within two weeks of treatment. Further, in a study of patients with bipolar disorder who were stable on lithium, It was concluded that lithium actually decreases sensitivity to light.
CCPR’s Verdict: Although more research needs to be done, amber lenses may provide a low cost, low risk intervention for patients with bipolar disorder and is certainly a promising option.
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