Is Bipolar Disorder a Circadian Rhythm Disorder?
More than just a mood disorder? The link between manic-depressive illness and the amount of light in the day.
The Frontier Psychiatrists is a health-themed newsletter. This article is both scientific and personal. It’s about circadian rhythms and whatever bipolar disorder turns out to be. I will use Manic-Depressive Illness and Bipolar Disorder interchangeably in this writing… please consider subscribing! I am trying to stick the landing with a resource section at the end—feedback on that is welcome.
Manic-Depressive Illness was the name for what we now call Bipolar Disorder. I am not a fan of this rebranding. I don’t get to make the rules—the “branding” of psychiatric conditions is a product of the American Psychiatric Association, which is responsible for the publishing and subsequent royalties on the Diagnostic and Statistical Manual for the Diagnosis of Mental Disorders, now in its 5th edition with a Text Revision. It’s the DSM-5. It’s a best seller. This column is not about that topic.
Bipolar Disorder and Cycles of Day and Night.
My early life was marked by feeling bad, and I was not good for a long time—the first 24 years of my life. Like clockwork, every fall— I would have a depressive episode. Winter usually brought mild mania in my first 24 trips around the sun. Summer could have symptoms of mania as well. Spring would have another depressive episode. The real “clockwork” time for severe depression was the 2nd and 3rd weeks of October. I felt it coming. I was not alone. I noticed a pattern of low mood…here is some of science behind why “mood” is tied to the seasons of the earth.
Circadian Rhythms Matter in Mood Disorders
Circadian.
adjective
PHYSIOLOGY
(of biological processes) recurring naturally on a twenty-four-hour cycle, even in the absence of light fluctuations.
For depressed mood in people with bipolar disorder, a reason for this relationship between season and mood is the “math on the light in the day.”
The rate of change in darkness over the day changes over the year, and math fans will recognize we are talking about what calculus calls a derivative. The amount of sunlight you have on any given day changes over the year, but the rate also changes! The fastest rate of change (dx/dt) is in October. The math starts with a ratio:
We have a photoreceptor in our eyes that does not project to the visual cortex1. It responds to 460 nanometer light, which is bright blue.
It projects to the suprachiasmatic nucleu2 (SCN), which regulates circadian rhythm. Bipolar disorder is a circadian rhythm disorder even more than a mood disorder. 460nm light that you don’t even know you're seeing is the most crucial. Those receptors don't go to the part of your brain that sees things; they are not seen as different—they project to SCN. But our biology and mood respond to those brain-clock-changing wavelengths!
That 460 light? Evidence suggests it regulates mood in people with bipolar disorder. Mania can be prompted with bright blue wavelength light. Longer days in summer have more mania in manic-depressive patients. Conversely, “Virtual darkness3” is an evidence-based treatment—using glasses like these— for bipolar disorder.1
If you put on “sunglasses” that block out that one wavelength of light (460nm) for 14 hours a day, mania will abate in 70% of individuals in clinical trials. As a therapist, I practice— with bipolar patients— one evidence-based type of psychotherapy called interpersonal social rhythms therapy, an adaptation of IPT, which includes the understanding that circadian rhythm dysfunction is core to bipolar disorder.
I Tried to Avoid Medical School Because I have a Manic-Depressive Illness.
I intentionally did not take any classes that would allow me to attend medical school at Amherst College. I knew I had an illness— I thought if I got depressed, I wouldn't be able to do medical school, and I was scared. I made a lot of conservative decisions, some of which I stand by to this day. I’ve never gotten drunk. I have never had more than a few sips of alcohol in my life—five is the sip count over 44 years. I was not popular at college parties. I never smoked pot. I have never used a recreational drug. I avoided pre-medical classes. I avoided what I imagined would be an abject failure—medical training. This is because I was used to every October—from age 16 through age 24—bringing depression and disaster to my ability to perform academically. This cycle of daylight created a roadblock— in my young mind —to working towards being a physician. I imagined myself completely beholden to this light-dark cycle. I built my life around that fear.
I did another career first—as a recording engineer. Yes, that is why I have podcasts and music for my readers!
The irony of this theoretically manic-depressive illness-informed avoidance of medical school? My life was not adjusted according to best practices for young manic-depressive biology. I was working in a recording studio—where much of the action was overnight, and even in the daytime, there was no natural light!
Working overnights, I couldn't help but notice— “I'm miserable; this is an overnight job for the past nine months.” It wasn’t “October” that was the problem. It was a lack of well-regulated daylight that didn’t have wild variations throughout the year. I went from avoiding the potential of depression once a year to ensuring an unhealthy amount of daylight all the time! Imagine how much of a good idea that is for someone with a manic-depressive illness. It's not. I didn’t have terrible doctors. These were details about day and night that plausibly could have been pointed out…but were not—that photoreceptor for 460nm was new science in the 1990s! I graduated high school in 1997.
Not all things that are “valid” psychiatric problems are in the DSM. Not every valid detail is addressed with the same weight. The wrong understanding can lead to the wrong life choices. I didn’t understand that daylight mattered. I now live in a very widow-heavy apartment. I do not close the blinds. I wake up with the sun.
Bipolar Disorder: It’s a Circadian Rhythm Thing, Maybe.
Resources for bipolar disorder:
An Open Letter to My Bipolar Disorder.
Does Lithium Prevent Suicide in Bipolar Disorder?
Favorite books of mine: Amazon affiliate links!
Just Like Someone Without Mental Illness, Only More So
The best textbook on the topic is by Jamison and Goodwin.
Touched with Fire: Manic Depressive Illness and The Artistic Temperament
Treating Bipolar Disorder (IPSRT Manual by Ellen Frank)
Podcasts include:
Bipolar Disorder: Myths Busted
Owen Muir on “Before You Kill Yourself.”
Living as Yourself is a Life-Saving Gift.
Care for bipolar disorder? I still do that:
My colleagues and I provide treatment at Fermata in Brooklyn, NY, and Acacia Clinics in Sunnyvale, California, if you need help for you or a loved one.
Tosini G, Ferguson I, Tsubota K. Effects of blue light on the circadian system and eye physiology. Mol Vis. 2016 Jan 24;22:61-72. PMID: 26900325; PMCID: PMC4734149.
Ma MA, Morrison EH. Neuroanatomy, Nucleus Suprachiasmatic. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK546664/#
Phelps J. Dark therapy for bipolar disorder using amber lenses for blue light blockade. Med Hypotheses. 2008;70(2):224-9. doi: 10.1016/j.mehy.2007.05.026. Epub 2007 Jul 16. PMID: 17637502.